If Gay's baseline chemistry is high from the start, changes won't be detected.
If there is another "clear" untectable designer steroid then of course it will not be found.
Gay may be perfectly clean and Bolt may be perfectly clean and that would explain no positive tests.
I just don't like the rationalization of picking one athlete to be clean and one to be dirty without more than a hunch.
I would go on to say that I would raise my suspician for an athlete like Shawn Crawford who worked with Trevor Graham considering the rsults from Marion Jones, Tim Montgomery, Antonio Pettigrew and Justin Gatlin. Hard to think he won an Olympic Gold medal clean while training with this group that have known steroid users.
And as you gather this evidence of known drug users, many who never failed frequent tests, it gets harder to think that Gay and Bolt ran faster than them without help.
So it's hard to single out accusations on anyone without strong evidence.
I will not award a clean champion. That can never be proved.