It's pretty obvious, since ALL your bolts rusted and the caliper faces were discolored, that something acidic was applied that attacked the finish. The parts didn't care who
applied the harsh cleaner. I'm sure you were careful, but clearly your car wash used something strong. Our local car wash uses a very strong wheel cleaner and, on my rare visits, I ask them to skip that step.
The September 2012 issue of European Car Magazine has an excellent article on wheel cleaning - "How to Clean and Protect your Rims" on page 120, with input from Mike Pennington and Mike Stoops from Meguiar's. They make a range of wheel cleaning products and give the following advice:
You also need to be aware of what's behind the wheel, because strong cleaners can damage the finish on aftermarket brake calipers, rotor hats as well as suspension components.
Even the center caps need to be considered, plus the lug nuts and some inner wheel barrels are occasionally left uncoated. It's a minefield out there!
It's essential to always address the most sensitive material when cleaning. So, while chrome is the toughest material that withstands the strongest cleaners, a chrome cleaner could ruin the finish of uncoated aluminum or powdercoated calipers, for example, turning them an unpleasant milky white.
Here's the complete article - WHEEL CLEANING
Hope this helps!