Picture yourself at a bar on Saturday night: A not-so-cute guy tries to chat you up, then after you turn him down once…twice…three times, you still can’t seem to shake him.

So why can’t guys take a hint?

Studies routinely find that men think women are interested even when they’re not (um, we could’ve saved them the trouble). Now, a new study, published in Psychological Science, shows which guys make that mistake and why.Researchers asked 96 male and 103 female undergraduates to participate in a “speed-meeting” exercise, where they spent three minutes talking with each of five people of the opposite sex.

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Before the meetings, each participant rated his or her own attractiveness and desire for a short-term hookup. After each meeting, participants rated their sexual interest and attraction toward that person.

The results? Men on the hunt for a hookup were more likely to overestimate women’s interest, especially when the women were hotter.

But sadly, the cute guys you might want to flirt with didn’t make that mistake—it was less attractive guys who think they’re hot that overestimated women’s interest.

There may be an evolutionary explanation for that tragic twist of fate.If a guy makes a move only to discover that the girl isn’t interested, it may be a blow to the ego, but it’s not the end of the world. On the other hand, if he doesn’t and she is interested, then “he misses out on a mating opportunity,” lead author Carin Perilloux said in a statement. (And God forbid that any man misses out on a mating opportunity.)

MORE: What We Learn From Speed Dating Studies

Especially for guys who are just interested in casual sex, Perilloux noted that they pretty much have to take it wherever they can get it. “They are limited mainly by the number of consenting sex partners—so overestimation is even more important,” she said.

No wonder girls travel in packs to help each other fend off the sleazeballs.