Posted mainly because I'm pleased to have discovered this before Amber.

New Scientist: "Bad guys really do get the most girls."

The traits are the self-obsession of narcissism; the impulsive, thrill-seeking and callous behaviour of psychopaths; and the deceitful and exploitative nature of Machiavellianism. At their extreme, these traits would be highly detrimental for life in traditional human societies.
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Jonason and his colleagues subjected 200 college students to personality tests designed to rank them for each of the dark triad traits. They also asked about their attitudes to sexual relationships and about their sex lives, including how many partners they'd had and whether they were seeking brief affairs.

The study found that those who scored higher on the dark triad personality traits tended to have more partners and more desire for short-term relationships, Jonason reported at the Human Behavior and Evolution Society meeting in Kyoto, Japan, earlier this month. But the correlation only held in males.

James Bond epitomises this set of traits, Jonason says. "He's clearly disagreeable, very extroverted and likes trying new things - killing people, new women." Just as Bond seduces woman after woman, people with dark triad traits may be more successful with a quantity-style or shotgun approach to reproduction, even if they don't stick around for parenting. "The strategy seems to have worked. We still have these traits," Jonason says.
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"They still have to explain why it hasn't spread to everyone," says Matthew Keller of the University of Colorado in Boulder. "There must be some cost of the traits." One possibility, both Keller and Jonason suggest, is that the strategy is most successful when dark triad personalities are rare. Otherwise, others would become more wary and guarded.

Huh. I confess, I don't think this has anything to do with dating as such. Assuming these results hold under replication, I'd think it would be because those traits are successful when rare generally, rather than because of some kind of mythical "women like bad boys" factor that the pathological nice-guy types whine about. I mean, look at the "dark triad" qualities.

1. self-obsession
2. lack of regard for others
3. plotting

Those seem like qualities that, in sufficient rarity, are good at getting people what they want in all aspects of life -- business, politics, etc., as well as interpersonal relationships. It just so happens that the mating part of it is the bit that is most immediately (although not solely, not even in the least) evolutionarily relevant.

Recommended reading: Bryan Skyrms, The Evolution of the Social Contract -- discusses the conditions under which cooperative strategies can become dominant in evolutionary game theory models. Hmm... I wonder... for a world of mostly decent blokes and a smattering of assholes, ought we to be looking for some model that yields a lyapunov stable equilibrium of cooperators?

Addendum: also, I haven't read the study, but I'd be concerned about how careful they were about the direction of causation. It might be that males who are more sexually successful for other reasons (having hot bods, having money, whatever) display these traits because they suffer fewer social (sexual) sanctions for doing so.