Only if the person is unable to tell if you’re actually engaged or just humoring them. Most people are actually pretty good at reading social cues.

sometimes.

I remember talking to a doctor once (in a social situation). We were talking about non doctor things and he mentioned that most people find out he's a doctor and start talking about medical issues.

I think this happens to some people (doctors, lawyers, police).

And to a smaller extent it happens to all of us (sometimes). Older people might talk about divorce, or their operations, or their kids.