I definitely see Clark wearing goofy or flashy (no pun involving Marvel's speedster intended) socks, but I think that in his Superman persona, he would wear either solid red or solid yellow socks to keep to his simple, primary-colour scheme. That's assuming, of course, that he is wearing socks at all. I could also see his uniform having foot covering built into them as an extension of the cloth used in the leggings.
As an aside, does anyone know what Dean Cain wore under the boots on the show?
Joy,
Lynn
