Mike B is absolutely correct. I've used the California Duster for many years. I don't understand the principal of the dirtier it gets the better it works but it is true.
You will also see a lot of the guys at the shows using a spray product that is made to be misted on small areas at a time and polished off immediately with micro fiber towels. My son (Terry B.) does the spray stuff but he has a $10,000 paint job on his '53.
I just dust and go.