THe question in my mind is how deeply adn widely the corruption flows. If somebody could be stupid enough to keep a-dopin', then somebody else might be clever enough to bribe the right folks to plant the right stuff.
Now, egos being what they are it may be more likely an athlete will want that thrill and taste and feel of victory, as in crossing that line first with that euphoric (if pain-laden) thrill - badly enough to figure "I won't be caught... I'm doing x, y, and z" or "they're all doing it so they can't bust us all!" ... or any of the things we put together to rationalize irrational behavior. I don't know. I don't think the testers are necessarily *anything* like "clean" either, though.

I think too many people take competition just too seriously...