Actually, I get the OP's point. If any of us were barely getting into the dark side, or perhaps bought a watch off craigs list or the bay thinking it's gen, at what point would we want to know the truth? Is ignorance truly bliss? If I were the pam fantasy's fantasy owner, I'd rather know from a person in the quiet then be full blown called out. I'd be grateful and actually be curious to know more about better looking watches.
It seems that the owner is nice and likes watches from the sound of it. OP, I would not use the term call out as it incites members here to think that by being nice about it, you're coming off as pretentious. Instead, call it educating the owner and hopefully help him avoid getting scammed again if that was the case.
As OP stated seen in a meeting, meaning this guy has the potential instance where he could get called out by a colleague or business associate. It could get ugly fast for that guy. Worse case is: He gets mad because he knowingly bought it as a fake and has been trying to pass it off as gen. In which case OP walks away and shares no inside knowledge on better reps. Best case: guy is grateful and learns more about watches.