A friend of mine was at a club where Eddie Money got 2nd place in a Eddie Money karaoke contest.
That Superman one, though...who would see a man in a suit and glasses and come to the conclusion that it must be a Clark Kent costume? If the claim is that they didn't realize the person wearing this "costume" was Christopher Reeves, they wouldn't have anyway as he was basically an unknown actor at the time of filming. Before they agreed to cast him, they had already declined, and they were down to even auditioning a producer's wife's dentist.
If anyone walked down the street dressed as Superman you'd likely get more attention than if you dressed in a Clark Kent-ian fashion.