Though mostly I think the Clark Kent disguise works because Superman is such a great actor. Remember how well Chris Reeve played two characters? The glasses were believable enough a disguise, all we needed all this time was a good enough actor!
100% agreed, here, esp. since I've seen this in real life, so to speak.
My girlfriend is Russian so she knows nothing about the Superman mythos growing up. She watched Superman: The Movie with me for the first time. First, she was incredulous when I told her that Clark Kent and Superman were played by the same actor. She genuinely believed she was seeing two different people. Second, she had a much harder time believing me when I told her the two men were the same guy in the movie only acting and dressing differently. Without the foreknowledge our culture has about Superman/Clark Kent, she was genuinely convinced of the separateness of the two identities.
The same goes for Jason Isaacs playing the dual roles of Captain Hook and Mr. Darling in a recent Peter Pan movie. Isaacs' acting was so superb I almost didn't realize he was the same actor in both roles (which was a masterstroke of casting that adds another disquieting aspect to the undercurrents of Hook's approaches to Wendy). Most people don't even get the hint I got and thought two actors played the two roles as it usually is done.
