Back when I had a Meridian 208, was when the "green marker" craze came through. Being a graphic designer, I just happened to have some green water-based markers (you shouldn't use solvent-based markers like Sharpies, because the solvent in their ink will damage the lacquer on the CD, and because water-based markers have very opaque ink that dries matte, whereas solvent-based markers generally have transparent or transluscent inks...)
I treated a few of my CDs, and noticed a small difference. Some discs seemed a little more "clean" and had slightly better resolution. But most just sounded somehow "different". Not better, not worse, just different...
Am I a believer in green markers? Well, it depends on the CD. But I can say that those water-based markers were a REAL pain to use, because the ink tended to bead up on the polycarbonate. Sometimes you had to put on three or four coats over the course of several days to get an even coating all the way around, and even when it was on, it tended to flake off if you didn't handle the CDs very carefully...