I've used some of that headlight polish stuff. On one slab (NGC) it had very little effect and I was disappointed. Last night I tried it again right before photographing my new 1921 Merc ( PCGS
slab) and it worked amazingly. There had been a big scratch and scuffed area on the reverse concealing the entire lower half of the fasces, but it's virtually gone now. So I guess I'd say YMMV.