Hateful lowlight: Doping during competition
OK, so technically Lance Armstrong isn't an "athlete" anymore, but he's such a self-serving egomaniac that he deserves dominion on this list. For the majority of his career, Armstrong equated his own athletic success with surviving cancer, which blurs the line between the man (a liar and a cheater) and his cause (inspiring cancer survivors). In the wake of his doping scandal, Armstrong delivered a half-hearted confession to Oprah and recently said it's "impossible" to win the Tour de France without doping.
Bottom line: this is why we shouldn't make heroes out of people who are just good at riding a bike. The cyclist's character became a fetishized symbol of hope and Armstrong, the fraud that he is, reveled in the spotlight.