I think the dealer is a 'safe' place to have your ride washed. However, you won't get as high quality a wash from them.

I have friends in Cleveland, Oh who will take their X to the dealer was during the winter to get the salt off the paint and from the underbody (free wash if you bought your ride there). During the winter, this wash is fine for them because it serves the basic purpose. However, when they want a very good wash with the nice shine, no swirls etc, they take it to one of the 'special' washes in the area (they never wash the X themselves).

Bottom line, I think the dealer is "safe" but not very good for a car wash.