This article is from the rec.audio.* FAQ, by with numerous contributions by Bob Neidorff others.
In a nutshell, save your money.
A CD player "reads" information on the disc with a laser light
beam. Some believe that if you put a green stripe on the very
perimeter of the disc, then the light beam will not reflect
around inside the disc and will more clearly pick up the data.
Scientific studies of the data coming off of the disc have
failed to show any difference between a virgin disc and a green
painted disc. I have not heard of double blind listening
comparisons that have proved that there are people who can hear
the difference, although many have performed uncontrolled tests
with positive results.