what's the moderation policy/etiquette for calling out obviously LLM-generated comments? doing so feels like more heat than light, but letting them pass by without saying anything feels like another step towards a dead internet.

I think you've got to handle them on their own merits. Ultimately humans can write like AI and AI can write like humans, but a good answer is a good answer and a bad one is bad. Karma and moderation already have plenty of ways to handle inappropriate answers.

I think the value of the interaction matters. Who ever got an LLM to reply wanted to learn? be thoughtful? argue? what? And will this interaction be valuable for anyone replying to it? reading it? I think yelling at the void and hearing the coherent echo of a million people is not the same as having a conversation.