Depends on the car wash equipment. I've used them plenty of times, saves loads of time. Sadly far too many Auto Car Wash operations are going out of buisness due to poor maintenance and as a result people are using the manual labour outlets offering multiple clean, wash, wax etc. options.

A decent Auto Car Wash will have fresh soft brushes for front, back, sides & roof, apply water first, then wash with a wash solution, then apply a wax if required, dry etc. The brushes should be fairly light on the bodywork and no marks should result, I've never had any problems with them. On the other hand manual car washes can result in swirls and scratch marks as a result of dirty clothes being pressed too hard onto the paintwork.

It's worth considering using a Waterless Car Wash system as an alternative to the above two types of car wash.

I much prefer the manual hand wash gangs.

As Mike says, thery need to be properly maintained. I believe they're fine unless your car is less than about 6 months old, as they can damage new paintwork. Or is that an old wives' tale?

I think they recycle the water they use. I'm sure they filter it to remove the dirt and grit, but how do they get rid of the salt in the winter?

Used to be a problem with the old cellulose paints, which were much softer. My father once aquired an Austin 1800 cheap, as it had a completely matte paint finish from being whirly-brush-washed since new.

Not a problem with modern, epoxy based paints. I get to claim washes for my fleet car, so it runs through every couple of weeks. Nearly four years on, the paint is unmarked (well, unmarked from washing......usual stone chips etc.)