How can those drug masking products for passing drug test really work for pot?

I know that testing labs do not really look for ';THC';(.9--tetrahydrocannabinol), itself. The look for its metabolite (11-nor-delta-9-tetrahydrocannabinol-9-c鈥?acid), which is the subsance your body converts THC into. I also know that this metabolite is stored in your fat cells. Since the drug testing labs now can perform validity testing on your pee, looking for tip-offs that the specimen may be adulterated. Such as the presence of Creatine, nitrates, pH, specific gravity, etc.. How can those companies that claim their product will ';cleanse'; your system really believe it works..?





And in case your wondering, no, I am not up for a drug test. But I know someone who was. He took some stuff called Vail. He said he followed the directions to the letter, but they still found pot in his system and he had to back to jail...How can those drug masking products for passing drug test really work for pot?
Because they may indeed flush your system by water and vitamins or some substance and when you take them for a drug test they will not back a guarantee- they just say that you should not have used illegal drugs. They word their package very shadey.