Well Lance Armstrong is all over the news since the release of his confessions to Oprah Winfrey. What a big dissapointment to cycling.
What about Rosie Ruiz Vivas who joined the the 84th Boston Marathon in 1980 a mile from the finish line and supposedly won the race in record time. She was found out because people were suspicious of her build which was not what a marathon runner was expected to look like. And then it was discovered that no one remembered her entering the race.
Then there was the Comrades Marathon in South Africa is a 56-mile (although there is some controversy about the exact distance) ultramarathon from Durban to Pietermaritzburg, and notoriously taxing. Sergio Motsoeneng placed ninth in tace in 1999 but he was caught out after it was discovered he and his brother had swithced places in a toilet along the way where they switched shoes. But they forgot to switch their watches and footage revealed the brother who wore the watches on different wrists. He was banned for years, and Sergio returned in 2010 only to be disqualified again for testing positive for performance enhancing drugs after running 3rd.
Truth is stranger than fiction!!