I had my body man/painter buff my corner glasses. I held them while he ran his buffer over them. We used a mildly agressive compound (same as buffing clear coat). Worked pretty well, not perfect, but from 6 feet away they look it. Bottom line- try that first, it won't "grind" into the glass like others noted, but it might not get ALL of the scratches out. I think you'll be pleased with the end result.
