Is there any way to perhaps at least hide scratches in black bumper trim on older audi's? (100cs 92-94)?...

I've had good experience with a company called Creative Colors. They're a francise operation and I believe may be nationwide. They generally do vinyl/leather repair and refinishing work on interiors for used car dealers. They're mobile and generally work out of vans so they will come to you. I had both bumpers refinished on my 91' 100 for about $100.