This doesn’t make me particularly proud, but the first thing I thought of when 25-year-old tennis star Justine Henin announced her retirement Wednesday was “failed drug test.”

That is completely unfair to Henin, a winner of seven Grand Slam titles and a woman with a seemingly spotless record. But it’s the world we live in, or at least the world I live in, a world in which dark clouds are hovering constantly. It’s a world of Marion Jones and Roger Clemens. It’s a strange world.

Did you know Germany’s national champion in billiards tested positive in March for EPO, a blood booster? Billiards!

Did you know a Russian biathlete was thrown out of the Turin Winter Olympics because she tested positive for a stimulant? No?

Did you know a French surfer was suspended three years ago after testing positive for steroids? Dude, it’s true.

Did I mention France? Surely you know cycling has turned into a chemical farce.

Drugs are everywhere, no matter how big or small the sport. They’re in high school sports. They’re rampant in some professional sports.

What it proves is that people will do just about anything to get ahead. It also proves a few drugged-up apples can ruin the entire barrel, reputation-wise.

So when someone of Henin’s stature suddenly announces she’s hanging up her racket, or whatever tennis players do when they retire, evil thoughts start gathering. Eyebrows are raised. She says she lost her passion for the game? At 25? Hmmmm.

Upon hearing the Henin news, I immediately thought of Martina Hingis, who announced at her retirement news conference last year that she had been accused of testing positive for cocaine at Wimbledon. She angrily denied the accusations, but the International Tennis Federation eventually banned her for two years anyway.

Again, there is zero in Henin’s record that suggests anything untoward. If she was using steroids, she was using the wrong ones. She’s 5 feet 6 inches and 126 pounds. But the cloud that hangs over sports these days whispers a cynical “uh-huh, sure” in response.

It’s the same cloud that makes you question the accomplishments of almost anyone who has reached 500 home runs in the past 20 years. It’s the same cloud that makes you wonder about fast times by swimmers and sprinters.

(The first thought of a friend of mine, after hearing about Henin’s retirement, was that perhaps she was about to be indicted for something or other. It oddly made me feel good for not being the only one with dark thoughts. Then again, he’s a sports writer too.)

It is not a “witch hunt,” as former Cubs manager Dusty Baker once called the pursuit of the Barry Bonds/BALCO story. It’s nothing that active. It’s a stalled weather system over your head. It’s a depression that tugs at you. It’s a feeling of helplessness.

You ask yourself: Can I trust anyone or anything in sports anymore?

I’m not happy with what all of this has done to me. It stings that the first thing I think of after a sudden retirement is something sinister. But it’s also a defense mechanism. Get zapped enough times, and you make sure you won’t get zapped again.

I hope she really is just retiring for retirement’s sake. It might start a trend.