I realize this is an older thread but I came across it and maybe I can help. I was a Program Manager for a few years at the company that makes nearly all Ford OEM emblems and badging including the Ford Explorer hood letters, Ranger fender badges, F150 & F250 etc. fender badges, Bronco lettering, Mustang applique, Powerboost logo's, ecoboost logo's, almost every Ford oval badge, and on and on and on. We also produced a lot of badging and other plastics for all other domestic and foreign automakers.
For piano black painted items that received scratched at times during manufacturing, we would use a heat gun to repair the finish. It is a self healing paint and the heat gun worked great. Other plastics like MIC grained / textured plastics, we would use a Mr. Clean Magic eraser and lightly scrub the surface with it to remove marks and light scratches. A heat gun works well for this also but you have to be really careful. These are really the best tricks for scratches and what is done at the OEM manufacturing level.