I will call out a girl for being a bitch but never for their looks, that's a really sensitive thing because they might be a bully because of their insecurities, and pointing them out may only make it worse or make them harm themselves.
I know this sounds a bit weird but when I was bullied by this girl briefly in high school (because of my grades, no less

), she was really very unattractive, horrible personality, and really had nothing going for her, but I never said anything about that to her because I felt sorry for her. And she already had no friends, no one liked her. My friends started targeting her and I made them stop.
Anyway I agree with the OP, physical things can't be changed and often a person has a bad attitude because they were bullied/ overlooked their entire life because of their looks, it's a cheap shot and I don't think it's right.