There's no magic to it. Water to dilute your urine. If say the cut off level for a postiive for THC metabolites is 35mg/dL then you drink water to dilute those metabolites to say 30mg/dL and you will test negative. Problem is some labs will check other values, like specific gravity, pH, creatinine levels to see if the sample was adulterated. Some won't accept a sample that is clear because its obvious that you drank a lot of water. That is where the B complex, vinegar, creatine stuff comes from. In the end its just the water.
I used to get drug tested weekly...i passed every single one, i would smoke the night before and pass the test 12-16 hours later.
Those cleansers are BS, look at the ingredients, they use diuretics, creatine and b vitamins, tell you to drink lots of water and charge you like 40 bucks a bottle. For 40 bucks i could buy enough of that stuff to last me for months of drug tests.