(I think that people who do things deliberately to make themselves ugly--whether they think what they did is ugly or not--are fair game to an extent, but only in the sense of some gentle fun-poking. Nothing vindictive. This includes people who are addicted to plastic surgery.)
@John_Scotus tbh unless someone directly asks you what you think of their appearance, you can file it under "nunya". What people modify to feel good about themselves isn't really a matter for commentary or debate, barring people getting things like Nazi symbols, which are a clear indicator that they're likely to commit a hate crime and want everyone to know it.
(I mean, I saw a woman the other day whose face muscles couldn't move at all because she's addicted to botox. And then there are those with face tattoos and bones in their noses. Gentle teasing, yes, if I knew them well. Discrimination or being deliberately hurtful? No.)