I do you feel about me tipping a overweight waitress significantly less than attractive ones.
I think it's unfair to them, is there some reasoning behind that?
A fat waitress with a skirt can't do her job well.
You have the power to tip what you want, but to discriminate about a person's size is pretty cruel. Either tip everyone regardless of their size or don't go to restaurants at all. You will be known as the tipper who discriminates after awhile and get poor service everywhere if you don't tip fairly.
I tip 15% regardless of their size. It's not like they'll perform better if I tip them more.
You're wrong, if you tip them better they usually do perform better. But regardless, it's wrong to tip based on the size of the person. I recommend no longer doing this, and tipping based on the performance of the waitress.