Strangely enough, I have less of a problem with that, unless the comments are sort of baffling. What do you reply to someone who tells you your poems are good, but way too poetic? A short "Thank you for your comment, I appreciate it and I'm glad you liked the story" is generally enough, at least on archives, which aren't geared towards lengthy interaction between writer and reader. With that, everyone is happy in most cases.

I haven't had enough people comment on my journals to know how it works there.