If what I see is only one or two stray flecks of 
paint, I might try to remove them with my 
fingernail - but then *only* pushing on edge of 
the fleck of paint, and not scratching across the 
acetate.

For anything more, I get a Q-tip and a tiny bit 
of rubbing alcohol. I go very carefully, fleck by 
fleck, since the alcohol will also remove all 
other painted or xeroxed lines that are on the 
surface of the cel should you accidentally run 
into them. I try to wipe the alcohol away before 
it dries. (And in case it doesn't occur to you, 
don't use tissues with lotions in them for this!!)

As to the plastic between the cel layers, leave 
it there. If you remove it, the layers will 
eventually stick together. If there is something 
wrong with the plastic that makes it unattractive,
simply cut out a piece of cel bag and substitue 
that - but make sure to cover the *whole* of the 
painted area and then some!

Many Sharp Smiles,
--Drac