If they're picking at one or two little mistakes that you didn't even know you made, that's one thing. Either they're a prick, or they're just trying to be helpful but end up looking like a prick.

If they're deriding your complete and utter inability to spell a coherent sentence "lol wut u can has loosid jream lulz", that's something completely different, and is something I support wholeheartedly.