It's a maturity issue. The nice guys have not found a way to capture her attention. Bad boys capture attention without trying...they are just who they are, and this always seems to stir up issues, problems, and thus, attention.
I have to say though, I have recently found a nice guy that I'm interested in. It wasn't his looks that grabbed me, but his mindset and conversation. I think that at different ages/maturity levels, our ears are tuned to certain frequencies, and our choices reflect that. When our mindset changes and we mature, then the differences in our choices are more readily seen. Be blessed.