[NotAnEconomist]

Setting aside the morality -- which is its own reason to treat people well -- it's damnably effective.

Something I got from a book on negotiating:

It doesn't matter how good of a negotiator you are, if you develop a reputation for being a jerk, you're going to fail.

Why?

Because for every room you're in being the best negotiator, your reputation is in ten, negotiating the other way and talking you out of deals you didn't even know about.

Conversely, if you develop a reputation for being a reliable partner and a fair dealer, then your reputation will do the hard work for you. People will talk you into deals without your input, because they want to work with people like that.

[gao8a]

This. Winning is not how can I rip em off. Winning is a feeling of fairness in all parties and repeat business.

[baron816]

I have a theory that women don’t like to negotiate because they think negotiating requires them to be tough and mean. But really, if you’re affable and charismatic when trying to make a deal, which should come more naturally to most women, then you would be in good shape.