how to clean a CD with toothpaste:
1) put a small amount of water on the scratch, being very careful not to get the water near the edge, as water tends to wick between the plastic and ruin the foil.
2) taking a tiny dab of toothpaste on your finger scrub gently in circles where the scratch is. After a while the toothpaste will start to dry and flake. Add a tiny bit more water/paste when this starts to happen.
3) The idea behind it is that toothpaste is a fine abrasive. (Take some and rub it between your fingers, you'll feel the "grit" to it.) It smoothes out the scratch's edges and makes it easier for the laser to pass, as opposed to a jaggy gouge that reflects the light at odd angles.
4) *WARNING* the wrong type of toothpase can stain the plastic or be to "gritty" and will make the CD worse. Please try on a garbage CD before you get the technique right
-Halkun
King of useless knoladge