I agree that general and polite comments after someone writes something that's too incoherent to follow (no initial caps, no para breaks, chatspeak, textspeak, typos and atrocious spelling) can be done in a way to gently remind the person that if they want helpful answers, they might want to see how others phrase questions. I've seen this on mainly adult sites where teens pop up with legit questions.
Where some native English speakers have to be careful is in assuming that the writer is in the same category. Luckily, I've never made this mistake, but I've seen people make fun of someone's writing, only to discover that the writer lives in Rome and his/her native language is Italian. I cringe when I see this.