What's the difference between Dwain Chambers and Darren Campbell? One of them's a convicted cheat, the other isn't? That's one difference. One's pharmaceutical short cuts cost his team-mates two relay medals, while the other, with laudable professionalism, made sure relay gold was won last Sunday in Gothenburg before dissing the ex-druggie in all but name? That's another.
But what Chambers should really be aware of is this: one of them is far more likely to die prematurely of a stroke or heart attack or multiple tumours, with the added delights of hair loss, spots and shrunken testicles to accompany him to his early grave. He should have a word with Gregg Valentino, who was the official possessor of the world's biggest biceps until the 'roids caught up with him and the biceps fought back.
In the wondrously titled The Man Whose Arms Exploded (Five, Monday) the former competitive bodybuilder spoke at entertaining length of his descent into drug hell.
"I definitely have a Napoleon complex," he said. "I hate being small." For 23 years, he said, he was drug-free. "Then the small thing took over. I decided I was going to juice my mind out."
In the process he began suffering from what bodybuilders - and now doctors - refer to as "biggerexia", anorexia in reverse, in which these sculpted hulks look into the mirror and see Victoria Beckham. His biceps reached 28 inches. In one of the many home videos Valentino recorded, he looked like he had a sack of potatoes hanging from each arm.
Then, thanks to all the steroid needles, one of his upper arms became infected. "It was like a giant zit," he said. "It was just loaded with pus." In an act of mind-scrambling idiocy, he operated on himself, and at several points in the programme he talked us through the video sequence with glee.
It's the grimmest piece of footage I've viewed since I had the pleasure of seeing Robert Maxwell's brains scooped from his skull in his autopsy video, as Valentino draws out syringe after syringe of clotted blood and pus from the grotesque swelling. "It looks like a murder scene," he said as the camera panned round the blood-splattered bathroom.
He eventually recovered from that, but in one sense his problems were just beginning. "There's not a bodybuilder on this planet who takes steroids who hasn't dealt in steroids," he said - and he was no exception. He became a big-time dealer, his wife kicked him out of the family home and he began a Bonny-and-Clyde affair with a fabulously beautiful Puerto Rican heroin addict called Julissa. "She was rough," he said. "She was in prison 11 times."
When one deal went badly wrong, Valentino found himself on the floor with a rifle in his face. He was saying his prayers, or whatever drug dealers do when they're about to have their head shot off, when the door burst open and Julissa stormed in, guns blazing. "She saved my life by shooting him in the ass," he said.
She died of an overdose not long after, then Valentino was busted. He lost his career, his family and his gym business. Now he works out in a tiny basement and shows his home videos to anyone who'll watch.
To him, the moral conundrum is simple. "Would you rather have your kid on heroin or on performance enhancers?" he asks, before advising us, superfluously, "don't look at me as a role model." Funny and articulate, he's devoid of self-pity.
"I sold my soul to the devil," he said, "and I had to bend over. When it was time to collect I stuck my ass in the air and said, 'be gentle'." The trouble is, the devil's generally a rough old sod. Just ask Dwain Chambers.