Well, when it all comes down to it, Smallville is only a show. So, a lot of makeup and such is put into the development and creation of episodes. They make it look real because their suppose too, but that doesn't mean it's so. I think everyone knows that. LOL... In a outtake in the 3rd season, Sam Jones was about to touch the simple and Tom jerked back, but he then told Sam that he was only joking. He berkata he had to do that at least once. So, I think we can role out the fact it was real. I think it's like a tattoo, that is really detailed in creativity.
