[bjwebster]

OK, This is a tough question because things differ from place to place.
First Off, What do you mean by wipe down? If you mean your drying it afterwards, I would say thats a no-no. There no way that spraying off the car you got rid of all the dirt. This will introduce micro-scratches and swirls.
I use a synthetic sealent on my car so its gonna take alot more than some cheap car wash to strip it off. But if you are using a carunuba wax, it doesent take alot to strip it off, so I would agree that that soap certainly isnt going to prolong the life of your wax.
But your right by not spraying it directly at the paint. What worries me the most is that alot of those coin op places recycle water. I really dont like spraying old, dirty water onto the surface of my car so....Its sorta one of those things you will have to decide.

--Bolton