Tyler Hamilton had declared his innocence against doping charges. Doug Pensinger/Getty Images

Thursday was a relatively good day for U.S. cyclist Tyler Hamilton. I say "relatively" because Hamilton was informed by the International Olympic Committee that he will be allowed to keep the gold medal he won last month. It appeared that Hamilton's might be the fourth gold medal from the Athens Games stripped for doping, but he was let off the hook when a laboratory employee froze, rather than refrigerated, Hamilton's 'B' blood sample, rendering it useless for testing.

But Hamilton also learned on Thursday that his Swiss-based professional cycling team, Phonak, confirmed that a second test on Hamilton's blood from the Spanish Vuelta on Sept. 11 found traces of another person's blood. The presence of another individual's blood in such a test indicates that the athlete has received a transfusion from another person, a practice long called "blood doping," and one which invigorates the body's ability to transport oxygen to tired muscles.

If Hamilton is doping, he's yet another athlete who challenges the stereotype that makes U.S. fans feel like they can spot a doper a mile away. Hamilton's a small, doe-eyed 33-year-old man from Marblehead, Mass., a working-class athlete from a working-class hometown. Not one month ago, I was on a plane worked by a flight attendant from Marblehead and upon learning that I work for Sports Illustrated (discerned by looking over my shoulder as I pecked away on this laptop; happens all the time), she couldn't wait to tell me how proud the entire village was of their boy Tyler. Why not? Hamilton selflessly worked as a domestique on Lance Armstrong's first three Tour de France victories and then went off on his own. I interviewed Hamilton in northern Spain just before the 2001 Tour and found him quiet and mature, yet clearly focused on someday winning the big race for himself.

Last summer he raced nearly the entire Tour with a broken collarbone and, getting a nice piece of the Olympic feel-good karma, talked about winning his gold medal this year for his deceased dog. This story played as only Olympic stories can. None of this makes Hamilton clean, although it makes many people assume he's clean. Or must be clean. Or should be clean. The essential problem here is that being a sports fan should be a simple avocation. Cheer for your team or your superstar. Feel happy when the team or the athlete does well, feel badly when the athlete or the team doesn't do so well. Sports fans like debate, but they're not so good in the murky world of drug testing. Like my colleague, Tom Verducci, wrote this week on the subject of Barry Bonds, "these are complicated times.''

Hamilton is just, of course, the latest test case in a 15-month slice of the doping continuum that has been as frenetic as any in the history of the use of the performance-enhancing substances. It started when track coach Trevor Graham sent a THG-laced syringe to the U.S. Anti-Doping Agency and while all the activity since then is not related to THG (although much of it has been), sports fans have been tested nearly every week.

Bonds and Armstrong are, of course, Exhibits A and B on the trust docket. Bonds has done more -- by far -- at an advanced age than any slugger in history with a body that is radically different from the one he had in his mid 30's. His personal trainer, Greg Anderson, is at the center of the BALCO investigation.

Armstrong is an American hero, a brilliant athlete whose triumphs in six Tours after his triumph over cancer has inspired millions of people to, as Lance says, "Live Strong.'' This is all good. It doesn't mean Armstrong is clean. Or dirty. But it's inescapable that Armstrong is the greatest performer in history in a sport -- and an event -- with a long history of doping offenses. It's also inescapable that sources keep emerging, claiming Armstrong has used drugs. On Wednesday, SCA Promotions, a company that owes Armstrong $5 million for winning his sixth Tour said that it is withholding payment until it sees Armstrong's medical records, citing claims of using banned performance-enhancing drugs in the book L.A. Confidential, the Secrets of Lance Armstrong by David Walsh and Pierre Ballester. Armstrong has long and vigorously denied doping and has sued SCA, claiming it doesn't have the right to question Armstrong's victories. (And maybe SCA is just trying to duck paying the $5 mil).

Perhaps journalists didn't have the right to question willowy Greek hurdler Fani Halkia's gold medal run in the 400-meter hurdles at the Athens Games. But she admitted to training with disgraced sprinters Kostas Kenteris and Ekaterina Thanou and her winning time in the race was faster running over 10 hurdles than her best time for 400 meters last year, without hurdles. Such performances stretch believability. Maybe it was the excitement. Or maybe not.

The easy out in all controversial situations like these is that the athlete has never tested for drugs. Bonds (who is tested once, in season, a joke) has never tested positive. Armstrong has never tested positive. Halkia has never tested positive. NFL Players almost never test positive and when they do, they get slaps on their meaty wrists.

Last May, while she was in the vortex of the BALCO storm (she still is, but in the post-Olympic lull, the storm has briefly abated), Marion Jones conducted a press conference at which she kept repeating that she had been drug-tested "160 times'' and never come up positive. Finally, a journalist in attendance pointed out to Jones that the entire BALCO affair was based on a drug that had been undetectable. Jones had no answer for that question. Nobody does. Perhaps drug-testing is getting better. Athletes were tested for Human Growth Hormone at the Athens Games. (Of course, it's the 1996 Atlanta Games that have come to be known as the Human Growth Hormone Games). Track and field's distance running record book was trashed in the late '90s, long before authorities developed a test for blood-boosting EPO. Now they test for EPO, but EPO is passé.

This story could go on and on. And it will, probably without resolution. In this regard, Thursday was not a great day for drug-weary sports fans relatively or otherwise. Another day, another doping scandal. We have nearly reached the point now where sports fans have to find their comfort zone regarding their heroes and their teams.

For me, it keeps coming back to this: I'm not convinced that anybody is clean. Are you? And do you care?

Sports Illustrated senior writer Tim Layden weighs in with a Viewpoint every Friday on SI.com.