Treating used CDs to make them play as if brand new?

Question

A friend and I bought some used CDs from a big store. Before we left, they wanted 'to clean them up' for us and disappeared into a back room. We got home and the discs played flawlessly. For about six uses, and then little flaws started to emerge. They had obviously treated the discs in that back room with some substance to make them play perfectly until the 7 day guarantee was up. WHAT WAS THE SUBSTANCE? They refuse to divulge what they used.

Answer 1

I cannot attest to the effectiveness, but a salesperson at a video rental shop near home claims what they do for rentals returned dirty or scratched is clean with spray "Pledge" (furniture cleaner) using a "clean soft cloth".

I don't expect the lemon scent is necessary!

I tried it once and the disk played fine. But other than that try at your own risk.

If it works I would guess the solvents help remove dirt and the wax fills scratches in the surface.

For what it's worth ....