My 1 experience wasn't successful. In June 2014 I spent $250 to have my CSS detailed before I went to Parade in Monterey. This was before I did my own detailing. For fun, I'd entered in the concours. I didn't even bring a bucket of cleaners and micro fiber towels on the trip (total rookie move). I also put a new set of Ferodo brake pads on before I left in prep for the 2 day DE at Laguna Seca after Parade, so by the time I got to Monterey, I had a nice new batch of brake dust covering my 15 spoke wheels. Pulled into Monterey late Sun afternoon only to find everything in Monterey closes early on Sun except a Home Depot. The only thing they had that
might clean brake dust was Simple Green. Took my CSS to a hand wash place and liberally sprayed the Simple Green on the wheels before washing. Maybe knocked 50% of it off but defn not all of it.
The next day 'on the lawn', I did my best cleaning my CSS. The guy next to me had a super clean silver / blk Cayman S with a crew of 4 ppl working on every minute detail. I knew I was in over my head. When the judges came around, I explained my brake dust situation. They looked over my car and only docked me a .5 pt for the brake dust but docked me a full pt for finding a crumb in the passenger seat (duh, I was eating pretzels on the 1700 mi trip out so I'm not surprised they found 1 crumb). However, I finished 8th out of 12, so there were 4 dirtier cars than mine. The guy next to me finished 2nd, so I guess he needed 5 guys.
But I had the last laugh. After the judges had been by, I left to look at the other cars and unbeknownst to me, Hans Peter Porsche stopped by my car and had his picture taken next to it. Guess he liked it and it matched his green pants. Bet HPP didn't stop by the CS next to me. I got an email with the pic link a few wks after I got home.
And I don't remember seeing my neighbor at the DE on the weekend.
Sorry for the lengthy comment, but that's my exp with Simple Green & brake dust. Maybe it would work better with a brush.