Bitchy women get better divorce settlements: true or false?

It depends. It depends first of all, what you consider a “bitch”, and second of all what you consider a better settlement.
I think an assertive woman who was not so abrasive that she turned off the judge might get a “better” settlement than a doormat who rolls over and agrees to everything her husband and his attorney asked for and offered. If by assertive then the woman is a bitch, then I suppose you could say that bitches sometimes make out better in a divorce.
Men by nature seem to be tougher negotiators than women. They want the most and they want the best. Women are more used to accepting, taking what they can get and playing nice. In a divorce negotiation, a wife is better served if she is well prepared and if she is extremely knowlegeable about all aspects of marital property. To the extent that she can provide her attorney and the court with a plenary account of their assets, the better her position at the negotiating table. Sometimes, it isn’t even a question of bitchiness. The numbers will speak for themselves.
Some women come off as “unreasonable”, “shrill”, “angry”, “begrudging” and “whiny” during their divorce.  These are such stereotypical terms, but there it is. This can happen. I try to counsel clients to watch their body language and watch the emotions when they are in front of the judge. Sure, your feelings need no explanations. But in court it just tends to give your husband the edge. He immediately looks like he is the reasonable, mature, “victimized” spouse with you there carrying on with all your hurt feelings. And that is why some women are branded with the “B” word too. It’s all the hurt that comes off as them being bitchy. And this can hurt the outcome for that woman, I think.
But a woman who is calm, in control of herself, knowlegeable, and assertive will do much better. This is a whole different type of the classic “B” and a hell of a lot more effective in getting fair settlements.