In addition to the above, it has recently been revealed that Carl Lewis failed three drugs tests prior to the 1988 Olympics, but was "exonerated" (in secret) by the United States Olympic Committee. Lewis had tested positive for three banned substances, pseudoephedrine, ephedrine and phenylpropanolamine.
This would be less relevant (given the prevelance of drug abuse within the sport) were it not for the fact that Lewis was unrelenting in his condemnation of drug abuse within athletics throughout his career. World's Greatest Athlete or World's Greatest Hypocrite? I wonder what Ben Johnson thinks?