An easy way to test if you will need an adhesion promoter for plastics is to take a small, non-visible, place and cut a small piece the size of a finger nail clipping.
Take that piece and put it into a glass of water, if it sinks easily and stays down, you can paint WITHOUT any promoters. If the piece won't sink or keeps floating back up, there are to many oils/solvents trapped in the plastic, and will require the use of the promoter.
I did not test all the pieces, but all the ones I did sank straight down. They were all the same kind of ABS plastic I believe.