Don't even think about skimming it, or using ANY spirit on it!
I use dilute bleach to get the crap out of some of my records, and it really does work a treat (contrary to cynical belief). I have also used it on acetate, with exactly the same results! Bleach doesn't corrode acetate like spirit does - it gets all ground-in crap out of the grooves, and the resultant sound quality is so much cleaner. If it doesn't clear the noise, then you'll know it's caused by scratches and general wear & tear, in which case there's nothing that can be done to get rid of it.
I'd experiment with a junk acetate first before hitting George Smith with bleach................