I worked at a glass shop, and if glass or mirror had over spray on it we would use #0000 steel wool, it is made to polish and clean glass and is very fine and will not scratch the glass. After you are done vac. up and metal dust from the pad, then clean with a good quality auto glass cleaner.
The S.O.S. pad has a soapy mixture in the pad and has never scratched any glass I've used it on...it might not be quite as fine as #0000 steel wool, but it's not like sandpaper either. I should have noted in my earlier post that this is FOR GLASS ONLY AND NOT TO BE USED ON THE PAINTED SURFACES such as the hood mentioned. Clay bar for that would work just fine.