I've been a red faced rosy cheeked person my whole life. Sun makes it worse and when I'm hot or sweaty I get even more red. Dumbass people I don't know seem to love telling me I'm red or sunburned regularly. It's so irritating because when I see some goth freak I don't comment on their ghost white skin or freaky tats/haircut/piercings. Nor do I tell anyone they're freckle faced or that they are cross eyed even if they are. I may compliment a stranger, but that's it. No matter what I say, it's always positive.
Depending on my mood I have 3 different responses to the people that offer their unsolicited opinion on my red face.
This is my most common response "ya know, you really shouldn't comment on a stranger's appearance unless you're going to say something nice." Usually this illicits an apology and I just say "don't worry about it" , as if I'm still not too happy about it but it's no bfd.
If I'm in not so good of a mood, I will look into their eyes and in a serious tone I say "thanks for pointing that out to me. Just so you know, I have an incurable disease that causes my face to be red. I'm really self conscious about it. Thanks for ruining my day". This also usually illicits an apology that I deliberately ignore. I make no eye contact and walk away. Hopefully the person I said this to will think twice before they comment on a strangers appearance next time because I made them feel guilty for hurting my feelings. They could also think that they pissed me off-which is good too.
My 3rd reply is if I feel like being an asshole. This largely depends on the person saying it and whether I feel they're just dumb or if they're trying to fuck with me to see what I say. If I feel they're testing me to see if I'll get pissed, they get what they're looking for. I instantly pick out any physical or unsightly flaw about them and say " Thanks for letting me know and by the way you're a (pick one) fat/bald/short ugly/skinny-fuck. Don't take it personally. You commented on how I look, so I just thought I'd return the favor" Usually this illicits shock and silence. Sometimes it's followed by an apology I ignore. As I walk away I say "maybe I'm red because I'm just really pissed off all the time cuz people like you feel the need to comment on my appearance when I didn't ask you to?"
People are so fucking socially illiterate. If you can't say something nice rhey shouldn't say anything at all.