What do I have going on here?

[Indygenerallee]

you use the scrub brush at your local car wash!!!  I have see people clean 4 wheelers after they went mudding at the carwash, That has to be the absolute worst way to clean your car, all that crap embedded in that scrub brush head and your engraining it into your finish. Hand wash it at home! 

[JB400]

There ain't noting wrong with washing your car at the car wash.  Yeah, I work at one part time.  When I wash the bays out, the brush gets it as well.  Feel free to take precautions and rinse it out yourself.   As far as car wash detergent causing that, I don't know, but anythings possible.

[Tilar]

No, he doesn't recycle his water and I always spray the brush down with the wand before I turn the brush on.  It's not salt because salt would come off with the brush.

[Indygenerallee]

Those brushes at the car wash don't do your paint finish any favors!