Why do girls date assholes?

One of my friends on Facebook posted this as a question to the universe today, and because I hear it ALL THE TIME, I wanted to address it.

My theory is that girls "date assholes" because "assholes" are typically the only guys that actively hit on them. No matter how you personally define asshole (or jerk, or whatever your favorite negative term is), the definition usually includes a large ego, and therefore outward confidence. Because (a lot of) the nicer subset of the male population has had little luck hitting on women (because they don't know how and fall into a myriad of common mistakes that are easily rectified by reading Screw Cupid and/or the upcoming male version of Screw Cupid I'm currently working on), they don't do it very often, leaving the female population to be approached by only the assholes of the world.

Ever heard the complaint "There aren't any good guys left!" - it's the same story, just from the other side. When the only guys hitting on a girl are jerks, she's going to assume that jerks are the only guys available - hence the aforementioned complaint.

Yours in the belief of a plethora of nice guys,
S

*Clearly I'm generalizing - there are obviously exceptions to the "only assholes hit on girls" statement, and the "nice guys don't hit on girls successfully" statement, as well as the millions of women who refuse to date assholes. I answer in generalizations to keep in line with such a generalized question as "Why do girls date assholes?"