I think its too grey an area to define as "bad boys" and "nice guys". I think at its purest level, the so called "nice guys" are just overly clingy, overly attentive, and so on and so forth. The "bad boys" are probably just confident men, self sufficient etc. This is more attractive to a girl - now the bad boy can then take the piss and cheat or treat her like shit, or he can be loving and caring, as well as confident and independent. The latter gets the long term win, the former gets a lot of different pussy.
EDIT: And the nice guys are probably way too considerate in the bedroom. Sure talk about what a girl likes and so on deep into a relationship and when having a conversation on the couch, but not whilst you are getting down and dirty "Do you like that? Is that good enough? Would you like me to touch your etc etc?"
Just grow some balls and get on with it! Stroke her, nibble her, suck her, lick her and then fuck her damn hard and don't be afraid to throw her into positions.Talk dirty, get involved. The confident guy will do this, the "nice guy" will pussy foot around.