I think it's interesting that you have such a noticeable discomfort with this sort of thing. I really mean this genuinely and not in a snarky way. If I were in your shoes I'd explore it more, because I've personally learned lots about myself from looking closely at my own odd pet peeves. You might have complicated feelings relating to play or performance. Your issue with him not seeming sincere doesn't make a lot of sense in my head because, of course, play is acting. It's pretending. It's performing. So it's always in a sense insincere, but also, simultaneously, very sincere in that the play-actor is wholeheartedly entering into this imaginal space. Maybe he's a bad actor, but the intention itself is there, or he wouldn't be doing it at all.