WD-40 didn't do anything at all. Acetone worked, but also left the black looking faded. The problem is that since the guitar case has texture, paint is inside the little grooves, so I really have to scrub to get in there, and scrubbing makes the top of the grooves take more damage. Since I'm dealing with paint on paint, I can't pick which color comes of and my case is going to get faded if I try to remove anything.