Batman does put the fear of...Batman into criminals...was thinking Superman on red K would put the fear of God into them. I was thinking the whole Clark Kent persona would vanish and all there would be is Superman.
Plus Clark on Smallville had lots of issues in season 2 on red K...that made him seem like a jerk...in season 6...still a jerk but the only issue he was dealing with was Lana & Lex getting married. I am thinking Superman on red K would have more attitude.
I am not saying he would be unleashing his inner demons...to say Superman is just a good ol' boy robot...which is what I'm getting from your comments is not correct.