Say Dale Earnhardt, Jr. wins some big NASCAR race and it's discovered later that his crew was putting a banned fuel supplement in the tank. Would Dale have to give the trophy back? Would it matter whether he knew about it? What if no one knew the substance was banned, would the hardware still have to be returned? You bet it would, sorry Dale. Even if the additive didn't make a material difference in the race, Earnhardt would still have to be disqualified.
So what about Barry Bonds? Should his records stand? First of all, nobody gains 40 pounds of bulk and thinks it's because of some arthritis cream he's using. But whether he knew about the banned substances at the time doesn't matter. He still had (has) an unfair advantage. Why shouldn't he be tossed out of baseball? Why shouldn't he have to return ten of millions of dollars to baseball fans? After all, didn't he negotiate contracts based on performace created by illegal use of steroids?