Detox drinks

So lately a few people that I know have been going through some legal trouble, and I hear every once in a while, "So i have a drug test in three days," or something like that. Getting to the point, all of them swear by whatever detox drink. I'm always trying to tell them to buy Quick Fix, and make sure they actually pass, or to at least make some other preparation than drinking the detox drink. The thing that gets me is, they always pass. Just last week my friend was at my house smoking, when he told me he had a drug test the next morning. I told him he shouldn't even be smoking right now, and he tried to tell me that he was fine because he had the detox drink. In the morning he drank the drink, and then filled it twice with water and drank it. He pissed twice before the test. He's a heavy smoker. He and I will go through an ounce in a few days. He took the test, and he passed.

Why do these things work enough for so many people to swear by them?

Alot of it has to do with body type and metabolism. For a lot of them dillution maybe whats really making them pass. Its a crap shoot with detox. Fine if there working but if they don't work once thats all it takes to screw up your life.