Good enough for a documentary

My son and I were talking about some movie star, whose name I can't remember now, being discovered in some common, ordinary way. I told him stories of ones I remembered hearing about who had been spotted eating in a restaurant, sitting at a bus stop, shopping at the grocery store, or walking down the hall of an office building. I don't know how we got on the subject and I don't know what our point was initially. But, the conversation ended like this:

ME: It would be so hard to believe. How would you trust that the person was honest? I can't imagine being discovered like that. You're just sitting in a restaurant somewhere and some big-time movie guy starts talking out of the blue about being in a movie. It doesn't seem like something that I could even imagine...

SON: Yea, not for you - unless it was a documentary.