There is no end to the stupid remedies I've tried. Nail polish remover is definitely one of them. Again many people swear by this as it dries out the cold sore. My experience with it is excruciating pain! This goes for all alchohol based solutions too, dabbing them onto a raw cold sore could bring you to the point of collapse and if not, a teary eye or two and a Chuck Norris award.
I've tried this remedy countless times usually out of complete desperation, a wedding the next day, job interview or blind dates! The list goes on. But I've never noticed a decrease in healing time. In fact I've often noticed the opposite.
Damaged tissue is infected more easily and will always result in slower healing times.
The theory behind using this is that acetone or alcohol will dry up the sore and destroy the virus. What you are in fact doing is destroying the tissue that's trying in vain to repair itself from the damage caused by the virus. Your poor lip is being attacked on two fronts!
My personal tip. If it's a fluid filled blister get a clean sterlised needle and gently pop the sore and gently drain the excess fluid. You can use the acetone to sterilise the needle but I'd prefer you use something a little less toxic. Don't damage the surroudning tissue of the cold sore by trying to squeeze everything out. Damaged tissue is infected more easily and will always result in slower healing times.