Having an absurdist attitude has been helpful to me in that regard. I mentally stand back and observe the situation from afar. How do I appear right now? What's my stance? My facial expression? I have trouble controlling them, but I have a default pleasant smile I can go to when I'm uncertain what to do. For fools, I have some standard phrases I use. "Oh!" "I see!" "Interesting!" "Well, I never thought of that!" "You're kidding me?" "Please tell me more" - all without a note of sarcasm. I fake genuine until I can find my escape or achieve closure. Still, takes time to recuperate from fools. I envision it at a distance like a really bad skit that I must participate in. Faking genuine or acting isn't too difficult after practicing. I ask myself, "What does this person expect from me right now?" and that's what I give them. I don't like doing it though.