Agreed, but....
I did once see a guy that really did fit the M.I.B description. Looked like a "grey" in a human mask. Dark almost black eyes. Very thin and sickly looking complexion. Walked real stiff like his knees couldn't bend the full range of motion. What really caught my eye about him besides the face and the stiff gait was he walked with his arms well out to his sides and his palms out flat, faced straight rearward. Like you would have to make a conscious effort to go walking around like that.
The only other time I recall getting a real eerie vibe off someone like that was when I did a vehicle service for some rich people in a Land Rover. The guy gave off vampire/satanist vibes and his mother couldn't speak but had the freak 75 year old with joyce wildenstein level plastic surgery. She had to wait in the car. Of course it was the Land Rover, which means everything takes longer. Anyways, I had this inner repulsion to their presence. Like a dark evil force or black clouds seem to swirl around them. Super strange vibe.