After reading here and there about why you shouldn't wash your vehicle at the "do it yourself car washes" I finally stopped and have been strictly washing at home for the past 6 months.
I wax regularly to help protect from the AZ sun, and recently clay barred (is that the right word? Lol) the truck and it's so smooth!!!
I noticed bird poo on my truck today and on my way home I decided to hit up a car wash to clean the truck real quick. I did all the normal stuff I always did high pressure rinse, tire degreaser, tricolor foam, foam brush, rinse, spray on wax then another rinse... Prior to taking my truck to the car wash, only washing at home, the water would ALWAYS bead up on the hood/roof as expected. As I rinsed off my truck tonight no more beads of water... I don't know if it was the car wash soap or the wax I sprayed on there but it must have stripped off all my wax on there!!! Wow!
Needless to say I will no longer be going to those places. I now understand how deadly these friendly looking places really are... Haha