I always spray out the foam brush with the high pressure washer before I use it on my car. If you spray the hell out of it, it gets all the dirt and other crap out of the bristles.Originally posted by heavyD
Don't ever use the brush at the car wash on your paint. It's full of dirt that will leave swirl marks on your paint. High pressure wand wash is the best way to clean your car and keep swirl marks away. New paint (especially Japanese) has soft clear coat that scratches very easily and the best way to have a swirl free job is to only touch your paint come wax time.
Generally this time of the year I'm far too lazy to manually wash my car though. The summer car gets a really good wand wash and is parked for the winter. My winter truck is a shitbox so it gets washed maybe once per winter when I can't see out of the windows anymore...