What paint for exterior plastic?

[jondecs]

Black gutters can fade with the elements and can look tired.

Agreed.

painting them with gloss can make them more attractive at a glance.

Never in a million years.

Allegedly maintenance free plastic
If done with a skilled hand and knowledge, with no brush marks, they will look perfect for another 10 yrs. Can take you to a few white gutterjobs (newish) but plastics have 'pinked' and one coat of thinned gloss with no abrading (scratchmarks will show thro) makes it hard to distinguish between factory and what I painted. still looks same 5/6yrs later~~
A house or bungalow should only take a few hrs.