Same problem here. A coworker explained it to me like this: "You see Clark Kent and you just subconsciously think, 'Oh, guy with glasses, harmless.' But you see superman and he's all, rarwgh! And no glasses. It isn't necessarily the shape of them, but something about just wearing glasses makes some men appear weaker/harmless, and weaker usually translates into feminine on some level. And that accentuates the rest of the fem in your face." I thought it sounded pretty logical. Well, minus the 'rarwgh' part >.<