The "500 drugs test" thing is a product of the Armstrong's PR machine, and has no basis in reality. One will look in vain for any verification of it.
The "in competition" tests are easily beaten. And, even there, Armstrong failed on some occasions to beat them. He tested positive during the 1999 Tour (although his after-the-fact "explanation" for the positive was accepted by, ahem, that those dastardly French who were otherwise "always out to get him.")
He also tested positive during the 2001 Tour de Suisse, but that failed test was "made to go away" by officials within the UCI.
Samples taken from Armstrong from the 1999 Tour de France were tested some years later after a urine test for EPO was developed. His samples produced "positives" in six instances (although, he could not sanctioned after the fact since the protocol would not allow for such under those circumstances). Even today there is news developing that other Armstrong samples, tested by USADA in recent times, have produced positive results, although that is yet to be confirmed.
As for out-of-competition testing, it has come to light in recent times that Armstrong was given advance warning of when the testers would be coming. The depth of the corruption within the UCI, which has been protecting Armstrong since 1999, is breathtaking in its scope.
What some people think is the reality here, and what is the reality here, is separated by light-years.
If he tested positive in 1999, why wasn't he disqualified then? That body is a total joke, if they can't come up with some consistent policy. And clearly they can't. They aren't judging everyone by the same rules. They have no idea what they are doing. If they can only decide 7 years after his last Tour De France victory, they don't know what they are doing. Their policy is only based on who you are, not what you did.
Personally, I think Armstrong is kind of a jerk, but that’s no justification for making special rules to punish him.
If they do come up with real physical/chemical evidence, good, then they've beaten LA fair and square, and taken a step forward towards clean sports. On the other hand if all the evidence that is presented is of the same sub-par standard that we've seen so far, then USADA has seriously damaged themselves and the fight against doping.
To those who writes about conspiracy theories about corruption within the UCI should also be aware that there is a turf fight between UCI and USADA - lots of money at stake. Not a proof one way or another, but reason to be a little careful before evidence has been put forward.