Yeesh, she is an asshole. The only excuse I can see for not tipping at least something is if the server is particularly rude or spectacularly bad at the job. I've refrained from tipping about four times in my life, I think, and those were because I just couldn't see rewarding the fuckwads I was forced to deal with. Other than that, I tend to tip pretty generously for the usual crappy-wages reasons.