It's worth remembering that HN is a common law system. If you want to nerd out about what the real, fine-grained guidelines are, follow Dan's comments; they're the site jurisprudence.
A corollary to the humor thing: insubstantial comments are problematic when they're negative and less problematic when they're positive or encouraging. That's a principle that goes all the way back to Graham. So you're generally going to be fine attempting a cheerful joke than you are trying for a sly dunk.
Malign people wrap antisocial stuff in order to get people to eat of it.
A joke with nothing inside it is just annoying and derailing. See the guy who always interrupts the conversation with a pun.
It is possible to wrap decent stuff with humor.