I find it quite mindblowing how some people assume that just because someone aren't content with something, whether justified or not, that they have no life. It's such a cheap argument to make.

I've said it many times before, but I'll say it again, being rude to someone will not make them change their ways. If someone says that something is bad, and you disagree, tell them why you think it's good and leave it at that. It's usually a lot more effective.