Well the scary thing is that guys like Mosley and Holyfield (at least to my knowledge) have never tested positive for PEDs. They just happened to be the unlucky one's whos lab was busted and receipts in their name were found.

That really goes to show you how effective drug testing in sports is, and you have to wonder how many of these guys who piss clean for all these years are actually using and cheating the tests.