6. Sperm wars. Women are designed to procreate with the strongest possible genes. Bad boys are sending an unconscious message that they have great genes, so they're not afraid of losing the woman by misbehaving. Nice guys are sending a message that they don't think their genes are good enough, so they won't misbehave.
7. Fear of intimacy. If a woman is afraid of intimacy, she subconsciously knows she can avoid it with a bad boy, since she can never get close enough to him to have to go there. A nice guy will eventually want a commitment, and that's scary.
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8. Low self-esteem: We don't feel comfortable with people who treat us better than we treat ourselves. If you don't think much of yourself, the bad boy is simply reinforcing your negative belief. A nice guy is treating you in a way you're not familiar with.
9. Sex. Women feel a nice guy won't be good in bed. They sometimes like to be manhandled and think a nice guy won't be able to take control and get the job done. A bad boy comes across as being able to deliver, even though that may not always be the case. Experts Agree: Cheating Is Not About Sex [VIDEO]
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10. Hot. Have you ever seen a bad boy who wasn't hot? I'm sure there are a few, but they wouldn't be able to get away with half the stuff they did if they didn't look so good. Meanwhile, when a woman describes someone as a nice guy, she means, "He's not hot."