I once hung out a bit with a guy who worked at a restaurant. He told me the usual stuff about how he would go around the tables taking orders and faking smiles etc. Then one time he went to the bathroom, did his business, and went out to wash his hands. He looked in the mirror to see if he had any dirt in the face, but to his shock he suddenly couldn't even recognize the person in the mirror. It looked vaguely like him, but something was off. He faked another smile, and the creature in the mirror followed. He made an ugly grimace, and the creature again followed. He smiled again, but this time the creature remained neutral.