Hmm. It just seems strange that you should suddenly be getting backhanded-insult-reviews if you haven't in the past. Maybe you got recc'd in a place with particularly snobby readers?

Whatever the reason: screw them. You don't leave "constructive criticism" (and I put that in quotes because some people actually give that which is helpful, but a lot of people just use that excuse to trash someone's work--and that's what this seems to be) on a fanwork if the author didn't ask for it.