July 26, 2012 --

Before triple-jumper Voula Papachristou even had a chance to take the field at the London Summer Olympics, the Greek athlete lost the support of the Olympic crowd -- and her chance to compete. The prospective Olympian tweeted the following with just days before the opening ceremony: "With so many Africans in Greece… At least the West Nile mosquitoes will eat home made food!!!" The racist tweet set off a firestorm. Papachristou was ousted from the Greek national team for "for statements contrary to the values and ideas of the Olympic movement." Papachristou isn't the first competitor in the games' history to let her conduct get in the way of her legacy as an Olympic athlete.

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Considering the discipline it takes for any athlete to reach the Olympic level, the surprising lack of it on display when Cuban taekwondo athlete Angel Matos kicked an official at the 2008 Summer Olympic Games stunned Olympic observers. During the third-place match Matos had against Kazakhstan's Arman Chilmanov, referee Chakir Chelbat of Sweden disqualified Matos for taking too much time to return to the match after sustaining an injury. Competitors are allowed one minute of injury time, at which point they have to ask for more time or forfeit. Matos then kicked Chelbat and later had to be escorted out of the arena. Following the dispute, both Matos and his coach received lifetime bans from participating in the sport. Matos later accused officials of taking bribes from the Kazakh team.

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Any athlete who shows up to the Olympics is there to win. Most will go home empty-handed, but are still grateful for the opportunity to compete. Bronze medalist Ara Abrahamian, a Swedish wrestler competing in the 2008 Beijing Games, wasn't satisfied with the result of his semi-final match. In an act of protest, he walked out of the medal ceremony, leaving his bronze on the wrestling mat. For his actions, Abrahamian was disqualified and stripped of his third-place finish. He and his coach were also briefly banned from the sport.

When Canadian sprinter Ben Johnson won gold in the 100-meter with a world-record time of 9.79 seconds at the Seoul Olympics in 1988, Johnson seemed to accomplish the impossible by beating American favorite Carl Lewis. The day after the race, however, Johnson tested positive for anabolic steroids, leading him to getting stripped of his title by the International Olympic Committee. For many Olympic observers, the incident would mark a new era in the games' history, one in which more and more athletes turned performance-enhancing drugs and were subsequently unmasked for cheating.

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Marion Jones might have the distinction of being the only athlete on this list to serve prison time following her Olympic disgrace. In October 2007, Jones admitted to taking banned performance-enhancing drugs at the 2000 Summer Olympics. She managed to win five medals, three golds and two bronzes, all of which she had to return. Although it might be unethical to compete in the Olympics while secretly using performance-enhancing substances, it's not illegal. Repeatedly lying to a grand jury investigating the use of these drugs is, however. Jones served a six-month sentence for perjury.

Boris Onischenko entered the 1976 Olympics in Montreal as a well-respected athlete in his native Soviet Union, representing his country in the pentathlon. The pentathlon consists of five separate events: shooting, swimming, horseback riding, running and fencing. Evidently, fencing wasn't Onischenko's forte. In a match against Briton Jim Fox, Fox insisted that Onischenko had been scoring without making contact with his foil. Officials investigating the Soviet's equipment found it rigged with wiring and a special grip to allow him to cheat. Onischenko left the games with his reputation in tatters, and was reportedly ostracized upon returning to his homeland.

Unsportsmanlike conduct isn't limited to individual sports, as was proven at the 2008 Olympics in a baseball game between the United States and China. Over the course of the game, seven players were struck by a pitch at bat, three were ejected, and two more players, one from each team, suffered injuries. The U.S. team ended up dominating the game all the same with a 9-1 victory. Baseball is no longer part of the Olympic program, but that decision was made by the International Olympic Committee in 2006, well before the game took place.

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Bad sportsmanship also rears its ugly head at the Paralympics. In 2000, the Spanish national basketball team captured gold at the Sydney Paralympics. One of the players on the team happened to be an undercover journalist, who announced that most of the players on the team were ineligible to play. Ten of 12 members of the winning team did not suffer from the intellectual handicaps they claimed, forcing the team to return their gold medals.

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Entire countries have also left a tarnished Olympic legacy. At the Montreal Olympics in 1976, the East German team captured an astounding 40 gold medals, with the women's swimming team leading the nation with 11 of them. Their competitors couldn't help but notice that their East German rivals appeared bigger, stronger and faster than any other athletes. Decades later, their secret was revealed. In order to demonstrate the superiority of its athletes on the world stage, East Germany implemented a widespread, state-sponsored program of doping its athletes with steroids. The competitors themselves were often caught unaware, believing they were in fact taking vitamins. Although the record books might not reflect this revelation, the damage done to these athletes physically as a result of steroid abuse is a lasting consequence of this scandal.

FULL COVERAGE: The London Olympics