I ask "what's the worst thing about working for $COMPANY", and if they answer with a variation of "the worst thing is how awesome it is" and there is time I push for something deeper. You get some quite interesting answers.
But these days with the meeting taking place over zoom and residential networks, just going still and staring is not certain to carry the same meaning!
I precede it with the softball "what's the best thing about working here" which usually makes them feel compelled to answer the "worst thing" a little more honestly.
As you said, it can often reveal a lot.