CD Repair?

I bought a Disc Doctor off of Ebay a few years ago. It is essentially as the others have descrbed: a crcular platform to hold the disc and a soft cotton pad to polish out the scuffs. You apply a cleaning solution and it will buff out the problems.

I've also seen some serious commercial CD polishing machines.
Doesn't make sense for most of us but I think these services and DVD rental chains may be using them.

Sometimes work, sometimes not. I have tried that service, and the success depends on the conditions of your disc.

I would not buy a used CD that was "fixed" in this fashion. The polishing takes away the scratch but in doing so, takes away layers of plastic, thereby decreasing the thickness of the material layer between the data and the surface. This would not be a problem if the laser within the CD transport could auto-focus, but this is not the case. CD transports & players utilize fixed focus lasers. This can reproduce errors, enacting the electronic error correction -- just as the scratch does -- so no benefit has been gained, only further destruction of of the disc...