cbreeze, i had the same problem with polly scale acrylic piant. actually, it was just interior green mainly, but it seems a few other colors would lift as well. everybody talks about the tamiya paints and thinner being to pricey, but i buy tamiya at my LHS and cheaper than polly. my recommendation is buy tamiya acrylics, ive never had a minutes trouble with them. they smell sweet as well.
ps tamiya dont have much of a color selection so you may have to learn to mix colors. its not very hard though, go buy you a color wheel and the primary and secondary colors along with black and white and youll be set. oh, buy some tamiya flat base as well. to me, mixing adds a little more excitment to my hobby, and saves space and money.