taking off masking tape residue, wd40, gooe gone, mineralspirits, all work good, a good linty rag helps too.

EXIT1965 - i'm begining to think that your an android, and have finger nails that are made of high-strenght metal composite made of unobtainium that is not from this plannet!!! i don't know what to say about your problem, definetly don't use the low-odur spirits, use the cheap stuff that stinks the worst. the time after you paint does'nt matter, if it wetsands good then it's fine to re-coat. but i know if i tried up to a month after painting i'm sure with enough force i could scratch the paint but not totally strip it for sure. maybe you should have never tried to scratch it off, i'd bet you'd be happy, and maybe after 4-6 months you would'nt be able to scratch it at all. i dunno, i'm sticking with my android theory lol