BEIJING - I don't think Mich- ael Phelps cheats. There's no evidence that he cheats. There are no whispers from connected or responsible people that he cheats.

Unlike Barry Bonds, his head has not grown to the size of a dirigible.

Unlike Lance Armstrong, he did not overcome cancer and defeat scores of competitors who would later fail drug tests in a sport where you apparently have to cheat to compete.

Unlike Mark McGwire, he has not added 50 pounds of muscle in his prime, nor does his sport turn a blind eye to drugs.

Unlike track star Maurice Greene, who never tested positive, he has not been fingered by someone who sold him drugs.

Unlike Marion Jones, he wasn't connected to BALCO, or any other illicit "co."

Unlike virtually every baseball slugger, sprinter and cyclist who has been linked to performance-enhancing drugs, Phelps has enjoyed a steady, predictable climb to greatness, and he volunteers for extra drug tests to keep his name, and his sport's reputation, clean.

So there is no reason to doubt Phelps, unless you've been burned so many times that you've lost the ability to trust sports heroes.

Phelps bears a curse:

He is a 21st-century athlete incinerating the record book while performing in a sport requiring strength, stamina and quick recovery.

Those are exactly the properties of performance-enhancing drugs that have made them so attractive to everyone from grotesque professional wrestlers to dumpy middle relievers.

While we have no specific reason to doubt Phelps, how many times in the past 20 years have we cheered an elite athlete, only to find out later that we were suckers? Recent sports history has resembled a long episode of "Punk'd," with Ashton Kutcher jumping out from behind a trash can to laugh at our gullibility.

McGwire and Sammy Sosa are said to have saved baseball, by leading us on a joyous season of monster home runs. We loved them. They broke our hearts.

Barry Bonds denied taking PEDs even while the evidence -- and his head -- grew exponentially.

Armstrong achieved one of the greatest accomplishments in modern sports, winning seven Tour de France races after recovering from cancer. He has never tested positive for PEDs, but it's hard to find a clear-thinking person, in Europe or here, who believes he could beat scores of cheaters without cheating himself.

The problem with drug testing is that it reacts to past scandals. Intelligent drug cheats are always ahead of drug tests.

And the problem with the suspicions that cloud sports these days is that there is no way to prove a negative.

Phelps can do everything right, pass every drug test, and anyone who wants to be skeptical or cynical can remain so.

Phelps knows this. In his news conference following his sixth gold, he said: "People can say what they want. I know, for me, I'm clean.

"I purposely wanted to do more tests to prove it. People can say what they want, but the facts are the facts."

Phelps is the story of the 2008 Olympics. His competitors have raved about him, saying he's from another galaxy, he's superhuman, he's unbeatable.

He set world records in his first six races. He has won more gold medals than any Olympic athlete in history. His excellence, like all of the best sports stories, defies explanation.

If you're a sports fan, you have to want to believe in Phelps. Film critics call the urge to immerse yourself in a fantastical movie "the willing suspension of disbelief."

In the case of Phelps the question is, are you still willing to believe?

Jim Souhan can be heard Sundays from 10 a.m.-noon on AM-1500 KSTP. jsouhan@startribune.com

The 4x100 medley relay was in progress at press time. Get results at startribune.com/olympics