Before reading BlackUnicorn's last post, I was just about to mention confidence.
I believe in both sexes, confidence makes you more attractive, lack of confidence will push partners away. People mistake it for "jerk vs nice guy" because jerks tend to be confident, and nice guys might be shy. But take a confident nice guy and a jerk with no self-confidence, and the nice guy is the one getting the ladies.
The problem is compounded when the nice guy becomes bitter. Then not only does he have no self-confidence, but everything in him screams "I resent you" to women. Not attractive at all.
Then there is a line where it's too much confidence, and that's when the person is just way too forward. It's a tricky balance, I guess, and I see how it can be easier to achieve when you don't care about the other person (no reason to be nervous about it not working, and therefore more confidence), making people who don't care (jerks) seem to have the upper hand... but in the end, it's really about confidence. You want to trust your partner. You want them to be independent. You don't want to have to constantly reassure them that things are okay. That's the way it usually works for both sexes.
Then you have people who prey on people with the lack of confidence/self-esteem. And it's annoying to see men go "women are so lucky, people take advantage of them. I wish women took advantage of ME!". I doubt you actually do. It's more damaging for your self-esteem than being rejected, I can assure you.