So Flak Munky...
What's wrong with my lovely new sponge ?
I don't get any marks or scratches (thorough jet wash first) and I dry off with AutoGlym Autodry artificial Chamois leather, which lasts years, leaves no bits or marks, and is fully washable. I have 6 of em !
Sponges are bad.....they pick up the grit and grime from the panels of the cars and stay on the sponge even if you put the sponge back in the bucket. You can see minor swirling and very fine scratching if the car is under a halagen light. Its not nice.
Wash mitts lessen the effect because the grit, dirt etc will come out of the mitt when its rinsed in the bucket.
There is a lot more info in the detaling bit of the forum about this and on other places on the interweb.
Alex