Depends on which side is scratched, of course. The working layer is actually on "top", the label side. If this surface becomes scratched, so that you can see light through it, there's no fixing it. The underside, which the laser of the reader shines through, is relatively thick, but is just clear plastic, so some pretty ugly scratches can be repaired. The goal is to smooth out the surface so that it doesn't block or distort the laser. Lay the disk with this side up on a SOFT surface--you must avoid damaging that printed side. You can then work on the scratch with any number of mild abrasives, even fine emery cloth for deep scratches. As the surface becomes smoother and more even, use ever finer abrasives, like toothpaste, jeweler's rouge, brass or silver polish, auto polish, pencil eraser, or even dry tissue (paper is abrasive). Just work carefully, pay attention and think through what you're doing. You can't restore plastic that has been gouged out, but you can give the resulting uneveness in the surface a smooth, even transition. In a pinch, I've done pretty well with just an eraser followed with a dry paper towel for minor stuff. I've even been known to shave down the edges of a scratch initially with a sharp blade. Once you understand that you've got some plastic between you and the layer that matters, you can relax a little and do what needs to be done. Of course, you could always buy one of those CD repair gizmos, but where's the fun in that?

wash them in the sink under warm water with a little soap, dont scrub just rinse and wipe dry from inside to outside in a straight line.

put some peanut butter on, and then wipe it off