when you go to detail a car, try your stuff, and it doesn't look good or doesn't do anything at all. I was doing a customers car, and was driving around houston. well apparently he drove through something and didn't know it. There are spots everywhere. I used the DA polisher and a cutting pad with DACP to get it off. IT wouldn't come off. i'll have to try a clay bar and rub reallll hard. luckily its only on one side of the car.