Steve,
I didn't even think about the false positive problem, which though not commonplace, is real.
Awhile ago, a friend told me of an acquaintance whose teenage daughter was having some physical problems and tested positive for some STD. When told, the girl went into hysterics, reportedly damn near suicidal. The parents questioned their daughter, themselves and how they raised her, and had a very tough time coming to terms with the new reality. The doctor who ordered the tests was recommending some serious treatments and with some haste.
The girl pleaded that she hadn't had the type of contact that the medical people said was necessary for transmission, and the family got a second opinion and a new set of tests. Guess what? The girl just had some common hygiene related infection treated successfully with pills, and not what the initial tests showed. Great news, but the trauma and distraught that the oringinal false positive generated apparently lingers.
Now, imagine if instead of this anonymous girl it was Tiger Woods or Phil Michelson whose test results were bogus. Like Lance Armstrong who will never be cleared in the eyes of the public no matter what the evidence is, the image of a "dirty" golf superstar wouldn't go away. I can just see the jealous, distance deprived competitor snicker under his breath on the condition of anonymity to a reporter about Tiger driving a 400 yard green. Or the hack at the country club who can't get the ball airborne remarking in the 19th hole for everyone to hear that he needs to get the same "prescription". Guilty without the opportunity of being found innocent.
Are there guys on the Tour taking illegal drugs? Possible. Are they having an impact on the game? I very seriously doubt it. The type of drug usage that apparently plagues other sports can't be beneficial for golf in the long run. Golf is a game where competitors within a relevant range, say upper 20s to 30s, seem to get better with age. Those who cheat are likely just the marginal players and they are only shooting themselves in the foot. The drugs will only speed the process of natural selection.
Now, I am just waiting for a GCAer to argue that steroid abuse is driving the desecration of classical courses as owners and members seek additional yardage. Or a thread "What tricks does the thoughtful modern architect have up his sleeve to overcome unfair, drug induced advantages of the cheatin' professional golfer". Can't wait.