they all leave a dirt film behind, and they are the worst thing you can do to your paint short of the drive thru car wash. the detergents used at a touch free are very harsh on paint and strip away your wax or sealant (even the “permanent paint coatings” get stripped away at a touch free, when i dont have time to do a proper wash ill go to a DIY bay and use the pressure washer to blast off as much as possible (first use the pre soak then rinse) not trying to hijack this thread just informing you. i will add that although they suck, as you said before: the profit potential is extremely high.