Theres never any harm trying to dry polish out a scratch, I remeber an old black PS1 disc (ridge racer i think) that was scratched to buggery. I picked out a old (100%) cotton t-shirt and buffed till my arm dropped off. It worked a treat. This is essentially what the CD repair kits do, buff the thing up.

Examine your scratched CD by looking closely at the bottom (non-label) side of your disc, with a bright light directly behind the disc. Hold disc about three to four inches from your eye, and look through the disc surface to verify that there are no pinholes or scratches which perforate the digital wafer (the metal piece inside of your disc.) If this metal wafer has been scratched through, you have lost digital ones and zeros embedded on the wafer, and that disc cannot be permanently repaired. Fortunately, a scratch through this wafer is extremely rare. If your disc clears this test, it can be completely repaired

taken from "http://www.cdrepair.com/"