Anyone remember the green pen? Man years back, they sold a green felt marker that actually painted the edge of a disc green, to absorb any stray red laser light. Many reviewers swore by it! And claimed it made a world of difference. But for some reason they are no longer for sale, apparently the difference wasn’t worth the trouble.
A good CD cleaning solution may or may not improve sound quality, but when your disc gets dirty, it may be worth having a special cleaner for it. Something that will evaporate away without affecting the plastic, or leave a soapy film. I recall some that claimed to fill scratches. Which may be a preventative measure to keep it from skipping at some point in the future. So just because there isn’t an instant improvement in sound, doesn’t mean it isn’t worthwhile.
Russell