Nice guys get one girl. Not-so-nice guys get more than one girl.
The reason why many girls like the bad boys is because girls for the most part feel constricted to within strict behavioural norms: they just can't do and look the way they really want because society has laid down firm rules on this, and women will comply with this because compliance is instinctual to a woman. When they see a bad boy, they think that he is not constricted to conservative social norms of any sort.... thus his bad behaviour. To hook up with him frees her too. Also bad boys have a fake self-confidence because they think they can do whatever they want (until they find out otherwise), and this self-confidence is also very appealing to women because they so lack it.
Lastly, "nice" guys tend to irk women because women think they are trying too hard to appease them. A woman chooses a guy based on his merits and personality (according to her), but the act of appeasement prevents her from being able to judge him. After all, no normal woman wants to be dating her shadow.
I've said this before in other threads on the same issue: just focus on making yourself the best you can be for yourself and don't give a fuck what the women think. Eventually a woman will be attracted to the confidence that is brought about by this. It is not hard muscles nor handsome face that a woman finds sexy, it's confidence.... and that confidence is shown in a man's stride, his eyes, the way he touches her, the way he bangs the hell out of her in bed, etc. This exudes confidence as well as power, and these are things women lack so they find it sexy.