I've read several stories where Lois recognizes Superman as Clark by looking at his chest. I, personally, don't think that one look -- albeit a long drooling gander -- at Clark's chest would mean that Lois would be able to pick him out in a line-up though. Perhaps I just haven't seen that many males (in RL) with bared chests like his, but are they really all that unique? That would be like Clark recognizing Lois's dead body because she gave him a belly dance once and he saw her navel (although, technically, I believe her costume covered her navel). Recognizing someone from a distinctive tattoo or birthmark or /cough, cough/ mole seems more believable.
