The guy at the dealership who "washes" the cars is probably the lowest paid kid on the payroll. I can only imagine what he is doing when he is not washing cars. I have seen them using sponges and actually sitting a bucket on the hood to make it easier for them to rinse out the sponge.
I must say, however, that my Lexus dealer is very sensitive to requests by customers to not wash the car. I think they get this request a lot. Recently they installed some kind of quick drive through washer that does not have anything touch the car. Still, I have a little note I tape to the dashboard when I take it in for service that says "Please do not wash this car today," and I have had no problem, but the level of service at the Lexus dealer is, as you might expect, generally higher than at most other places.