If someone goes into a car wash in a mud-caked car and if you're next then you can expect a pretty good beating with grit laden brushes.
I have seen sections of torn off aerials going round in the brushes.
I had a neighbour who always used car washes and his car looked like it had been cleaned with a Brillo Pad.
Another place I would never go is those 'hand wash' facilities.
You spend a few minutes watching and see how many times the drying leather gets dropped on the stony/gravelly floor then picked up and straight onto someones previously unscratched paintwork.
....and those charity/bob-a-job washes by school kids!!!!
No thanks...I'll do it myself!