[kqr]

I mean, it could still be a great question, even if you can't or don't want to answer it. It all depends on how you follow up. If you go, "Thanks, that's a great question. I don't actually have a good answer for you. I'll get back to you in a few days." And then actually get back to them with whatever you've found out, you'll build trust, even if you tell them it is a great question.

It's not about what you say, it's about what you do.

[yjftsjthsd-h]

Sure; a lot of this is heuristics and reputation. I personally suspect that in many cases, people do not associate the phrase with honest hosts who will actually try to answer, but it's definitely situational and depends both on the company culture and your own personal reputation.