I like the Shine Ola CD product also after trying many brands over the years, as said before no residue left behind, produces very glossy clean surface. Although 3M cloth is very good (retails for $4-5) I prefer to use large 100% cotton balls found in cosmetic dept....these produce even less scratch and more finely polished CD surface IMO. I also still like to blacken outer edge of CD with marker.
If you want to really test CD treatments before applying to precious CDs, apply to black CDR and inspect under halogen desk lamp. Like black paint on car this will really expose any ultra fine surface scratching or film residue left by product.....silver CD surface tends to hide this but it is still there. Be sure and check next day, some products will later produce haze/film even after you thought you completely buffed out day before.