Its not about defending the people who smoke pot and play in the NFL, its about understanding that some of them do. There are substance abuse problems, or possession problems quite often when it comes to NFL players. It's obviously easy enough to get away with as to where a player would try it, and possibly give up a million dollar salary, or at least some of that money. Drinking a cleaner is easy. You drink it a couple hours before the test, drink alot of water, and you take the test. Using the cleaner is much easier than you may think. He could drink it, just to be safe, even if he suspected that there would be a random drug test of the team that day, and have no side effect. It's not expensive, especially considering their salary.
I believe him. Probably most of the teams knew a long time ago as well.
Now looking at Talib's situation, this looks like it will hurt him pretty badly. One time isn't so bad, but that should have been a wake up call. The second time and third time are really going to make teams wonder about if this could be a problem in the future. This also shows that, at the least, he is hard-headed. Three failed drug tests. Come on.