You've answered some questions about online dating recently, but I haven't seen you mention dating sites that do criminal background checks. Do you think it's a smart idea to sign up for one of these, or is it just more marketing hogwash?

--Wondering

There's that very attractive man you see on a dating site who spends "a lot of time abroad" -- as one must, when primarily employed as a drug mule.

These dating sites that do criminal background checks probably seem like a wise choice. And they do offer their members something extra: a false sense of security. First, as one of the sites with "extensive background checks" admits: "Some people do manage to slip through the cracks. When in doubt, report it!" Charming. Kind of like telling bank customers, "If you notice armed robbers in the bank, feel free to tackle them while yelling, 'citizen's arrest!'"

Of course safety is a primary concern, but ponder this: Your friends don't background-check their party guests. Nor does the supermarket: "Hey, handsome, can't let ya into the trendy baby veggies section till we check for outstanding warrants." Also, not every person with a criminal record is someone to avoid. There's being arrested because your little brother left a pillowcase of weed in your trunk versus being nabbed for your armed carjacking hobby: "No, officer, I swear...nothing of interest in the trunk...um, that is, if we don't count the bound-and-gagged widow who owns the car."

There are countless articles listing some pretty obvious ways to protect yourself: Drive your own car to the date; meet in a public place; don't leave your drink unattended; and don't front anyone money. Another common piece of advice is to tell someone where you're going and whom you're meeting. Right. Surefire psychopath-stopper: "I told my roommate all about you, so you'd better put away that huge knife, buster!"

One thing you can do to protect yourself -- in online dating or any dating scenario -- is gag the voice that's shouting, "Happily ever after, here we come!" so you can pay attention to feelings that something just doesn't add up. These feelings often don't come out of nowhere. Research by neuroscientist Yue-jia Luo, among others, finds that our brain reacts to subtle signs we're in danger -- including ones we aren't consciously aware of. The brain messages the body to get ready for "fight or flight," adrenaline courses, blood gets pumped to our extremities, and goosebumps form on our arms (part of the physical basis of feeling creeped out).

Online dating, like all dating, involves risk. Assess your level of risk and whether it's worth the benefit -- immediate access to numerous potential partners. There are some crafty criminals out there, but odds are, the problems you'll experience will be the ordinary kind -- finding out that a guy has a few girlfriends and not a few girlfriends out back under the tomatoes.

I'm in recovery, and my best friend and I have sleepovers every few months. She's come over drunk and/or high on pot the past few times. It's not that it's triggering for me; she's just annoying and not herself when she's loaded. How do I ask her to not come over trashed?

--Sober

What does she do when she isn't visiting you -- attend Mass in a "Lucifer Rules!" T-shirt, pop by the animal rights march in a mink vest, and then park her ice cream truck outside the Jenny Craig meeting?

Though you know what you need to tell her -- don't come over trashed -- you're probably being tripped up by something I wrote about recently: how women evolved to be the confrontation-avoiders of our species, probably to protect their ability to have and care for children. In 1990, developmental psychologist Eleanor Maccoby reviewed the research on sex differences in communication and found what researchers continue to see today: A major goal of girls' (and women's) speech is "to be 'nice' and sustain social relationships," while for males, "the agenda is more often the single one of self-assertion."

Though being direct may not be natural for you, there are many things in our lives that aren't "natural": deodorant, motor vehicles, buying dinner at the supermarket instead of waiting behind a tree to club it with a rock. You're simply asking your friend to be appropriate to the situation. You could open with an air bag of sorts -- "I love you and love having you over" -- and then say, "But, from now on, please don't show up drunk or high for our sleepovers." Enduring a little discomfort in the moment should keep you from being commandeered into future "fun" drinking games like "Let's flip your cat over and do shots off her belly. I'll do vodka; you do water. Last one to lose an eye wins!"

A guy friend of 20 years and I once fooled around years ago. Though he has a girlfriend, he keeps throwing sexual remarks into our conversations, sending inappropriate texts, and asking me to send naked photos. I wouldn't be interested even if he were single, and I've been giving subtle hints, like "ha-ha...gotta go," right after he says something provocative, but it isn't working. How do I politely get him to stop without ruining a very long friendship?

--Upset

As a means of communication, hinting to a man is like having a heartfelt conversation with your salad.

This isn't to say men are dumb. They just aren't emotional cryptographers. Social psychologist Judith A. Hall finds that women are generally far better at spotting and interpreting nonverbal messages (from, say, facial expressions and body language, including that female specialty, the pout).

Women tend to use their own ability for decoding unspoken stuff as the standard for what they expect from men. So, for example, the longer a man takes to notice that his girlfriend is pouting (perhaps about what was initially some minor to-do) the darker things get -- with hate glares and maybe some cabinet-slamming...and then, the grand finale: "Hey, heartless! Time for a monthlong reunion with your first sex partner, aka your right hand!"

There's also a major sex difference in how males and females speak. A body of research finds that from childhood on, males tend to be direct: "Gimme my truck, butthead!" Females tend to be indirect (couching what they want in hints and polite and even apologetic language): "Um, sorry, but I think that's my Barbie."

Psychologist Joyce Benenson points out that these conversational sex differences line right up with evolved sex differences in our, uh, job descriptions. Men evolved to be the warrior-protectors of the species. This is not done with coy hints: "Oh, Genghis, you look so much more tan and handsome while invading our neighbors to the north."

Women's mealy-mouthing, on the other hand, dovetails with a need to avoid physical confrontation, which could leave them unable to have children or to care for the ones they've already had. However, in women's self-protectively not quite saying what they mean, they trade off being understood -- especially by men.

Making matters worse, research by evolutionary psychologists Martie Haselton and David Buss on the "sexual overperception bias" in men suggests that the male mind evolved to be a bit dense to a woman's signals that she isn't interested. Basically, men seem evolutionarily predisposed to make errors in judgment in whether to pursue or keep pursuing a woman -- erring in whichever way would be least costly to their mating interests. So, for example, you might eventually forgive this guy for all the tacky come-ons, but his genes won't if they miss that vagina-shaped bus into future generations.

In other words, in giving this guy "subtle hints," you aren't being polite; you're being wildly ineffective. Yank off the marshmallow fluff and tell him: "I need you to kill all the sex talk. Immediately. And yes, this includes requests for naked selfies." (Be prepared to need to repeat yourself.) If he really is a friend, he'll continue being one. He might even become a better one -- the sort you can call anytime, day or night, from the coldest place on the globe, and he'll say, "I'll be there with the sled dogs pronto," not, "Text me a shot of your boobs before you die of hypothermia!"

I love how my boyfriend smells, but I hate his new cologne. The smell literally makes me queasy. Is it even my place to ask him to stop wearing it? How do I tell him I don't like it without it being mean?

--Plagued

Try to focus on the positive: You find him extremely jumpable whenever he isn't wearing a $185 bottle of what it would smell like if sewage and verbena had a baby.

Unfortunately, it seems that his cologne and your immune system are poorly matched. Biologist August Hammerli and his colleagues find that a person's fragrance preferences correlate with their particular set of infectious intruder-tracking genes, called the "major histocompatibility complex." So, in not liking your boyfriend's cologne, it isn't that you think he's an idiot with bad taste; it's that your...I dunno, great-great-grandma got it on with some hot peasant with the "verbena smells like dead, rotting chickens" gene.

The science is your way in: "Sadly, your cologne does not play well with my genes..." Cushion the blow with something sweet, like, "I know you love it, and I wish I loved it, too." Suggest you shop together for a new cologne for him (ideally something that makes you want to get naked, and not just down to your World War II gas mask).

I'm a woman looking for a new boyfriend and considering various online dating sites. Some have long questionnaires, and they factor your answers into an "algorithm" to match you with the best possible partner. Are these sites significantly better than the others?

--Site Seeker

Most people will tell you they want to be accepted for who they really are -- yet those doing online dating rarely post profiles with stuff like "I like long walks on the beach, fine dining, and obscenely large breasts."

In light of this, sites using these compatibility "algorithms" would seem to have some added value. However, according to a massive online dating analysis by social psychologist Eli Finkel and his colleagues, this algorithm stuff mainly seems to be a "science!"-flavored marketing ploy. The researchers explain that it's "virtually impossible" for sites to do what they promise with these algorithms: "match people who are uniquely suited to one another" and who are likely to have a "satisfying and lasting long-term relationship" together.

As the Finkel team notes about the "uniquely suited" business: The evidence suggests that these algorithms are really no better at rooting out compatible partners than the matching most people already do themselves with sites' search parameters -- culling the herd of breathing, profile-posting humans down to, say, fellow Ph.D.s who are also weekend Satan worshippers. ("Shall we meet at the Starbucks by your office, or are you up for an afternoon of ritual goat slaughter?")

Even more outrageous is the sites' claim that this mathematical alchemy can identify two people who can have a lasting, happy relationship together who have yet to even meet. The researchers point out that the algorithms only measure the "individual characteristics of partners" (personality, attitudes, values, background). They note that this is just one of three essential variables that determine whether relationships sink or swim.

The other two are elements that can't really be sussed out before two people are in a relationship. One is the "circumstances surrounding (a) couple" -- like how they fit into each other's family and whether one loses their job or goes through other major stressors. The other factor is the "interactions between the partners" -- how partners communicate, solve problems, and support each other.

I would add an essential fourth factor that needs to be assessed face to face -- physical attraction. So, regarding those "29 dimensions of compatibility!" that one site advertises, consider, if you will, 30 and 31: discovering "this must be what dead bodies smell like when the detectives cover their nose with a hanky on TV" and "I'm as sexually attracted to you as I am to a stalk of wheat."

There's also the "garbage in, garbage out" problem (statisticians' shorthand for how poor-quality input leads to poor-quality output). It's unlikely that people are any more honest and accurate in filling out these questionnaires than they are in their online dating profiles. (No, sadly, outside the world of "gender-fluid" activism, being a woman isn't just "a state of mind.")

Typically, deception in online dating profiles is intentional; sometimes -- as research on personality finds -- we can't quite see ourselves as we really are. For example, take an item on one of these sites' compatibility surveys: "I try to accommodate the other person's position."

There are seven little circles on a scale to blacken in, from "not at all" to "very well." Well, okay, but do control freaks always understand that they're control freaks? Sometimes somebody seriously controlling might fill in "very well" on "I try to accommodate..." simply because they see themselves in the best light -- instead of the actual light: "I'm Stalin -- though I've never been able to grow much of a mustache."

Probably the best that can be said about these personality questionnaires is that they might lead you into a little helpful introspection. But otherwise, these tests seem as pointless as they are grueling (kind of like filling out an application for a bank loan for your personality).

This isn't to knock online dating itself, which offers really rapid, easy access to a lot of potential partners whom you'd probably never meet otherwise. However, it helps to have a smart strategy vis-a-vis the potential pitfalls, and that's meeting any person you think might be a possibility ASAP (before you have any long, bond-y text-athons).

Meeting pronto gives you the best shot at seeing whether you click, as well as spotting any vast differences between profile and reality. And as I always advise about first dates, keep it cheap, short, and local. Less investment means less disappointment if you find out a guy's lying -- or, maybe worse, if he's being honest: He really is looking for his "partner in crime" -- because one of the guys on his robbery crew got arrested last week.

My girlfriend and I broke up recently, so I'm back in the dating pool. Do you think online dating is a good way to meet people? If so, which are the best dating sites?

--Diving In

Asking "Which dating site is best?" is like asking, "Is pro basketball a viable career?" That question can only be answered by asking other questions, such as: "Aren't you a 47-year-old, 5'2" Ashkenazi Jewish woman with 20/80 vision and bad knees?"

To put this another way, context matters -- which isn't what they tell you in Datingsiteville. Save for specialty sites -- like those for farmers, the disabled, and people who relish a good flogging -- the advertising for these venues tends to be context-free: "Hey, everybody in the entire galaxy, get your lasting love here!"

Annoyingly, though most of us have a sense of what context is, nobody's done a very good job of defining it -- either in the dictionary or in Researchville, where I found a herd of dueling definitions, all so unhelpfully worded that they seem to be in secret code. So here's my definition: Context is a combo platter of the particular situation at hand -- like pro basketball, online dating, being a bad dancer, or being sexually attracted to woodchucks -- plus the details relevant to it that affect how you understand or experience the situation.

In the context of online dating, the relevant details include age, sex, the quality of the competition, and one's desired situation, as in: Do you just want casual sex, or are you holding out for something a little more, uh, black tie.

There are sex differences in when people are at their most appealing, because men and women tend to be at their highest "mate value" at different ages. This comes out of how male sexuality evolved to be visually driven (because the features men find beautiful -- youth being the biggie -- are associated with fertility). Women, however, evolved to go for "providers" -- men with high status and earning power. So, online dating tends to be more fruitful if you're a hot 23-year-old female espresso jockey or a 43-year-old male VP of a successful startup, but it can have some challenges for the 43-year-old female startup star or the 23-year-old dude who's the senior vice barista.

So the question is not whether dating sites work but whether the qualities you have and the situation you're seeking add up to more than a few tumbleweeds blowing around in your inbox. Because online dating success is shaped more by personal context (and plain old luck) than by the particular site you're on, you might experiment with two or three. If things go poorly, use online dating as a supplement to meeting women the retro way, like at cocktail parties, where you won't be competing with the 362 more genetically blessed males within a 35-mile radius. This vastly increases your chances of dazzling the ladies with your personality -- distracting them from how Mother Nature zoned out when she was handing out necks to your family.

This guy asked me out and suggested we meet up after his dentist appointment. He said he'd call around 2 p.m. Well, at 9:30 p.m., I got a "Hey" text from him and didn't respond. A friend said I shouldn't write him off so fast. Am I being too harsh?

--Dependability Fan

Individual bits of behavior are like cockroaches. You might see just one lonely roach twerking atop the toaster oven, but its presence suggests a whole colony of the buggers...gluing sequins to their exoskeletons and practicing their moonwalk behind the baseboard.

No, you can't always judge someone by a single thing they do, but this guy's one-word text -- seven hours after he said he'd call -- speaks volumes: "Holy moly, wouldya look at the time. It's 9:30, and I could use some sex."

How a person behaves is driven by their personality traits, which social psychologist Brent Roberts describes as habitual patterns of thoughts, feelings, and behavior that are relatively consistent across time and situations. Granted, there are occasions when impulse gets the best of us, and we'll say something like, "That wasn't really me." But, at least in some way, it really was, because even impulsivity is part of personality.

A person can resolve to act more conscientiously, but personality has a strong genetic basis, so they're unlikely to be as motivated to be conscientious as someone whose genes make them feel icky when they aren't. In other words, you were probably wise in nixing this guy, who couldn't even be bothered to fake respect for your feelings by supplementing that "Hey" with "Carjacked!" "Carried off by a raptor!" or "Still high on anesthesia in my blanket fort, having a tea party with G.I. Joe and my dog, Steve."

My boyfriend of three years cheated on me, and when I found out, he dumped me. I'm getting over it, but boy, it's a slow process. Some days, I'm fine, and others, I feel super sad or really angry. Is there some way I can speed up my recovery so I can get on with my life?

You wish him all the best, which is to say you hope a giant scorpion crawls out of the sand and bites his penis.

It's understandable that you're feeling overdue for a little emotional fumigation. But consider that there's an upside to the downer emotions and not just for the dry cleaner who's about to buy Crete after getting the mascara stains out of all your clothes.

Though we tend to see our gloomier emotions -- like sadness and anger -- as "bad" and the "whoopee!" emotions, like joy and happiness, as "good," evolutionary psychologist and psychiatrist Randolph Nesse explains that emotions are neither good nor bad; they're "adaptive." They're basically office managers for our behavior, directing us to hop on opportunities and avoid threats through how good or crappy particular things make us feel. As Nesse puts it, "People repeat actions that made them feel happy in the past, and they avoid actions that made them sad."

Nesse believes that sadness may, among other things, be evolution's version of a timeout. Note that a term psych researchers use to describe sadness is "low mood" (though it would more helpfully be called "low-energy mood"). Sadness, like depression, slows you down; you repair to your couch to boohoo, lick your wounds, and seek comfort from the two men so many women turn to in times of despair, Ben & Jerry.

And yes, there's value in this sort of ice cream-fueled Kleenexapalooza. Being sad is telling you "don't do that again!" -- while giving you the time and emotional space to figure out what exactly you're supposed to not do.

Because your emotions have a job to do, you can't just tell sadness and anger, "You're no longer wanted here. Kindly show yourselves out." They'll go when you show them that they're no longer needed, which you do by reprocessing your painful experience into something useful. Unfortunately, there are some challenges to this, because when you're upset, your emotions and all the things you're emotional about become a big tornado of stuff whirling around in your mind "Wizard of Oz"-style.

But what do we humans understand really well? Stories. And it turns out, studies on coping with breakups by communications researcher Jody Koenig Kellas find that creating a story about the relationship and the breakup seems to help people adjust better and faster. Essential elements in this seem to be relating your complete story in a "sequential" way (in order), having a narrative that hangs together and makes sense, and illustrating it with examples of things that happened and giving possible reasons for them.

The need to mentally organize what happened into a detailed and coherent story pushes you to reflect on and make sense of your experience in ways that less directed thinking does not. What seems especially important for moving on is making meaning out of the situation -- turning the ordeal into a learning experience that gives you hope for living more wisely (and less painfully) in the future.

Kellas' results dovetail with decades of research by psychologist James Pennebaker, who finds that "expressive writing" (similar to what Kellas recommends) speeds people's recovery from emotional trauma. But say you hate to write. Research by social psychologist Sonja Lyubomirsky finds that recording your story (say, with the voice memo app on your phone) also works. You could also just tell the story to a friend or a homeless guy at a bus stop. (Give him a few bucks for lending an ear.)

Finally, consider the difference between healthy storytelling, used to find meaning in what you went through so you can move on, and unhealthy "rumination" -- obsessively chewing and rechewing bits from your relationship without insight, solutions, or relief. Psychologist Susan Nolen-Hoeksema finds that this builds "a case for hopelessness," prolonging distress and recovery.

A powerful way to unbuild a case for hopelessness is by recognizing that you have some control over what happens to you. You get to this sense through accountability -- admitting that you have some responsibility for your present situation (perhaps by ignoring red flags and letting wishful thinking run the show). Sure, blaming someone else probably feels more gratifying in the moment. Unfortunately, this tends to lead to insights with limited utility -- such as the revelation that Cheerios, oddly enough, do not actually cheer you up (not even when paired with a lactose-free milk substitute such as Jim Beam).