It seems every question is great on the presentations I'm listening to, which is practically impossible. It's most likely a bell-shaped curve on the greatness scale. We should be hearing "that's a bad question" every now and then.

I heard a speaker once say "that's a [obvious pause] question" and the audience giggled because it was obviously a really poorly thought out question.

I've used "please phrase your question in the form of a question" when the person in the audience is using it as a platform to deliver a long speech.

Ahh I see you've never been to a physics conference!