The following may be difficult for some folks to grasp:
First off, women often like nice guys. Which is to say, they like those of us who have cultured within ourselves a modicum of civility, who take the ethic of reciprocity seriously, and give an even regard to others. This is far from being, as Glass Joe the Champ suggests, a huge, spineless pussy, but merely a gentleman.
However, they like sincerity [http://en.wikipedia.org/wiki/Sincerity] more. A jackass who treats a woman as an equal (and is a jackass to everybody equally) is favorable to a guy who is nice to her because from his perspective she's a vagina connected to a life-support system. (Consider those women who are nice to you, but regard you as a cash cow. How appealing are they?)
It comes down to this: we all want to be regarded as human beings, as equals. And many of us are so desperate to get laid (or to get a meal ticket) that to protect ourselves from such people, we've developed a great deal of (healthy) suspicion about the motives of otherwise desirable strangers. Much of our flirting and courtship is determining whether or not the other person is being genuine, only after which is compatibility considered.
So, Glass Joe, if you're nice to people to get in their favor (and later their pants), quit it. Figure out who you really are, and learn to be comfortable with that. (If you turn out to be cruel, angry and embittered, then you might want to work on your attitude, but that's a different matter entirely). But if you're a nice guy because you're just inclined towards cordial, polite behavior, keep it up and a worthy girl (or five) will eventually work this out and snatch you up. (Of course, you have to be in places where you meet new people. Loners like me don't get propositioned much.)
Secondly, women are as human as men. Which is to say that young women often don't know what they want any more than men do (other than to have sex with a healthy partner). Here in the United States, we are terrible at preparing our young people for intimate relationships or in the art of choosing prospective partners. Rather, they are usually left learning by trial-and-error what kind of girl / boy would be good match and they end up getting burned a lot. That said, you may be rejected by a woman who is otherwise a perfectly good match because she's not ready, has been hurt too recently, and presumes that all guys are unworthy. Don't take that personally.
But to surmise that being nice makes you look weak, or that women generally prefer jerks both oversimplify a much more complicated paradigm.
238U.
