It's called "Fetal Alcohol Syndrome", and it's nothing to make light of.

Get that child to a doctor!
Juuuust kidding.
My next door neighbor is a successful artist who paints primatives. He does very well, but I'm sure he's had to endure more than his share of I-could-paint-that-myself comments. He has an endearing personality and is very upbeat, but I have to think it's bothered him at times. I don't think I could take much of that.
If you pros are getting distasteful comments, I don't know if I'd ever be able to show my work in public.