WELL, after Warren's reference to Buscis2, I did a search and found the "Wash, Cut, Polish & Demagnetize" thread. Seems to say it all from most angles.....
I would, though, like to throw out a comment with respect to beveling the edges of CD's. I am not by any means an expert on laser technology or its application in terms of reading a CD. On the other hand, as a former furniture maker and an apprentice to my grandfather who was a MASTER craftsman, I do have intimate knowledge of beveling.
To accurately accomplish what I believe to be the purpose of the disc beveling would seem, to put it mildly, a daunting task, and perhaps the reason for sometimes reduced performance or mistracking. Off the top of my head, I can think of at least five areas in which the application of a chamfered edge on a flat, round, thin plastic disc could be problematic. First, the horizontal platform of the "jig" which holds the disc would require a very close tolerance so as not to deviate from a level plane as the chamfering cutter does its work. Second, and related to the first, a means to assure that the disc lies perfectly flat without warping would be essential. Third, one would have to assume that all discs are of the exact same thickness so as to avoid under or over cut of the chamfer cutter. Fourth, the perfect "roundness" of the disc would be critical in the absence of a compensating mechanism in the cutter head. Fifth, the chamfering "bit", need be exceedingly sharp and remain so for making clean, smooth, consistent cuts on something as inherently brittle and "chippy" as plastic - even if the actual removal of material is by means of grinding as opposed to cutting.
Again, I am not certain which, if any, of these criteria effects the transmission of the laser light to the disc. But, unless the machine used to do the cutting is of extremely high quality and/or very flexible, it would seem difficult to obtain consistent and accurate results.