THe best way to respond to anonymous GUESTs is to ignore them. Maybe sometimes they're lovely people saying sensible things. In which case the sooner they become members the better.

If for some reason they don't want to, or can't, or if they are in fact existing Mudcatters wanting to post anonymously, they can at least add a pseudonym to that GUEST to make it easier for other people. An unadorned GUEST makes it harder for others to say what they are agreeing or disagreeing with, or make any other sort of comment. If the GUESTs have some kind of hang-up about not being judged in the light of previous posts they have made, they can even use a different pseudonym each time. Seems a silly sort of game to play to me, but noone will know.

Where people don't even do that, the simplest and most sensible thing is just to ignore them, and assume that they are just stirring for its own sake - which I suspect is true most of the time. But since I normally make a principled point of ignoring them, that means I don't read them, and I can only go by the comments other people have made, so maybe I'm being unfair to them. Tough.