To remove paint transfer from minor scrapes with other cars, fences, etc., wet a towel with lighter fluid and lightly dab the surface, wetting the area for about 20-30 seconds. Then, rub the surface lightly and the transferred paint/color will disappear. Don't worry, it won't harm your cured paint, it just breaks down the bonds between the two paints there. WARNING: Contents are extremely flammable!
Courtesy of USA Today
