I'm potentially in the minority here, but what drove me up the wall were threads on a very interesting original post, whose comments were just endless chains of puns and lazy jokes, rather than any actual discussion.
A few are, but I think most aren't. It would be easy bot bait, but at the same time, it's also fairly context-sensitive in a way that would let a fair few users pick up on someone being a bot or not.
Although that doesn't mean that you can't have bots that are in on the joke.