How many people do you think have tested positive (ie, both A and B samples) for PEDs but were actually innocent? Are we 100% confident that all people who were caught actually were guilty? I'm thinking there's probably at least 1 person out there whose life is a living hell because of some mistake in testing.
Mistakes in procedures let a lot of guilty ones off
Water does not turn into wine outside of the bible
All scientific tests have a degree of error but before the results can actually be used with any degree of credibility the error has to be miniscule at best.
And in the unlikely event that there is a false positive, that is the reason for the B-test.
Between the two, unless there's tampering, it could be estimated at a degree of error of less than 1 in 10,000 and that's assuming a maximum level of error of ~1/100. The tests used are probably closer to 1/1000-1/10,000 range for the non-immunoglobulin-specific tests. Which is why the HGH tests aren't that great by themselves.
The two sample system makes that damn near impossible.
Ria van Landeghem got screwed out of the 1988 Olympics because of a major fvck up by the Belgian federation. The federation did drug testing prior to the Olympics to make sure that their athletes were clean. One judo athlete had a medical exemption to use steroids due to a testicular injury, but he somehow tested negative. Ria's A sample came back positive for a steroid. She vehemently denied any wrongdoing, so they went to her B sample, which also tested positive for a steroid. Curiously, the A sample and B sample tested positive for different steroids, one being water soluble and the other being oil soluble. Despite the massive inconsistencies with the testing results, she was banned by the Belgian federation from the Olympics.
Being in great shape she looked for another race, and went with Twin Cities Marathon which was a week after the women's Olympic marathon. The TC people pointed out that they do test for drugs, to which she basically said 'fine, test all you want.' She seemed rather pissed during the entire race and won rather easily in 2:28:11.