Swee, I have one word for your economic love thesis here and here: Elasticity.
With no scientific evidence whatsoever, I believe bad guys have elastic demand, i.e. an increase in price brings about a decrease in quantity demanded.
Now, it is somewhat true that bad guys do get their fair share of girls. However, most of these are often flings, obsession, flirtation and nothing more. The moment a girl realises that the price (cost) of keeping a bad guy is immensely high, her interest in the guy decreases, thus reducing the possibility of any long-term relationship.
So what's keeping the cost so high?
1. Well for starters, he wouldn't necessarily be treating her nice. And girls just love to be pampered.2. Next, his bad-boy antics may have seemed cool at the start but after a while, they just get annoying. Girls do want their guys to grow up someday you know.
So you see, I think you failed to take note of elasticity of demand, which would be a key factor in determining the attraction level of bad boys. But of course, I'm open to debate.