What's the problem with answering them? If 你 know they're perverted, just don't bother with it! This site is for 13+ for a reason 你 know, we can say pretty much whatever we want.
I wish people would. But some say that it's "fun" to do so, 或者 that "someone has to" but my thoughts are "um, no 你 don't, no one is forcing 你 too, and if we hate him so much and answering him isn't making him go away, so either we like his presence 或者 we're not mature enough to walk away."