Do you know how to clean an CD properly?
We do use *transparent* glass-cleaner spray (to reduce unwanted residues) 1st, then slight mist dryed by a microfiber cloth.
Black painting of the external CD edge - using a permanent marker - sometimes *may* (remember the GreenCD myth) help the reader to retrieve worst parts.
Using a better reader (that supports C2, slow speed ripping, etc) is, of course, the best option.
Hope that helps.