I don't know if that's the best question, thiugh.

First, if you're going to put them on the spot like that, in the middle of a room with their supervisor nearby, and ask them a question they weren't anticipating, the response is probably going to be a bit odd.

But frankly, I don't think I've ever been "happy" working anywhere, even in my current position. I get paid well, good benefits, work load isn't too much, people are nice, etc. but I'm not "happy" working there. I won't be "happy" working anywhere. Cause I'm working, and working does not make me happy.

That's almost the inverse of the shitty interview question "Why do you want to work here?" It's a ridiculous question for the majority of people in the majority of cases. "Cause I need money and your hiring."

I think a better question would be "Are content here? Are you heard, compensated, and treated well?"