Yeah, acetone can do that. I use non acetone based nail polish remover, it's great to use and doesn't seem to harm the vinyl. If there's anything stubborn, I coat the head with Oxy spot cream, leave it overnight then strip again with the remover and repeat as necessary till everything is removed. Butcher's mutton cloth (Often found as a polishing cloth at auto supply stores.) is good to use for stripping, it's not abrasive like say a scotch pad can be.
Thanks for the feedback. The know acetone softens vinyl and used the shrinking technique once, but this deterioration really caught me off guard.
I will have to try the oxygen bleach approach. I use pine cleaner for resin heads. I once left one in solution for over two months when I moved and it painted up just fine later, no effects whatsoever.