Surface reforming a CD, can be done by wet-sanding it with 3000-grit sand paper, and then polishing it with Polycarbonate polishing compounds. Some people have used Acetone vapor polishing methods, but I'd advice against that, since the vapors can attack the back side with the metalization.
For regular surface cleaning, I'd use no-wipe polycarbonate plastic cleaner. You can also use Isopropyl Alcohol for removing stains, and then follow it up with no-wipe PC cleaner.
When cleaning with water, get yourself a squirt bottle and de-ionized water. It's pretty cheap and cleaning a CD with that, is done in seconds.
However the real trick is not to get the CDs dirty in the first place. Put them back into their sleeve or jewelcase when not using them, etc.