[Lammy]

> I remember even heavily scratched cd's would work if you cleaned them with toothpaste of all things (?)

I've had even better results with this three-step stuff that's actually meant for plastics, with most scratches not needing more than step 2: https://novuspolish.com/

That works great for bottom-side scratches, but sadly it's not usually possible to repair any damage done to the label-side of a Compact Disc due to proximity between the label and the reflective data layer underneath. It's really common for well-intentioned people to remove discs from a drive and (in absence of the case) set them upside-down to "protect" them not realizing it's the worst possible thing they could do. All-over-print labels add an extra margin of protection over discs that leave the label's negative space as bare disc silver: https://cdn.hswstatic.com/gif/cd-crosssection.gif