I mainly focus on detailing but also offer powder coating and plasti dipping. In cases like yours, hard to reach and plastic trim areas, I keep Goo gone spray GEL handy. Spray....soak....and pressure off. for any other areas, I keep a some Xylene around (which is actually an ingredient to plastidip) and old tshirts or 100% cotton rags. Put some on Xylene on the rags and wipe over the plasti dipped areas and comes off.....but for the plastic parts i stick to the goo gone spray GEL.