Armstrong only ever won the Tour de France, he never even competed in the other great tours.
Actually he didn't win the tour at all.
Although I disagree with you that Contador is clean. the contaminated meat theory holds no ground. It's extremely unlikey that meat in Europe is contaminated with clenbuterol.
Most likely he used clenbuterol during training, they tapped his blood. He had a transfusion of that blood and due to a better test he got a positive result which they didn't anticipate. There were plastizers found in his blood, which strongly suggest a blood transfusion.
And I don't believe cycling is clean at all. One of the fastest tours in the history, and I'm supposed to believe they're clean? Froome did the 3th fastest climb ever on Ax 3 Domaines, faster than Armstrong on dope, and I'm supposed to believe he's clean?
But in cycling it's not different than in any other sport, 5 100m athletes got caught recently.
The chances of getting caught with a dopingtest is really small anyway. Most of the big names who got caught had dozens (sometimes handreds) of tests, not one positive, but got caught in other ways (Armstrong, Ullrich, Basso, Valverde). And it seems that most of their tests were negative, while in fact they wrer doped at that time. The test for epo for instance only gives a positive if the epo is taken withing 18 hours prior to the test. Most epo is taken in their training weeks, so it's easy to evade a positive test.