Hello. Thing that was bothering me for some time. It happens quite frequently that brand CD has a discoloration on the bottom side that looks like "stain" something like on the picture here: https://scontent-frx5-1.xx.fbcdn.ne...=03fd1f5b56a31f168da6715e62c8c66f&oe=59E158CC but mine are usually less visble and not so regular (rather swirls that concentric). I heard that CD polishing machines can create such visual effect, but it is not the case as it is on CDs that are taken straight from the store shelf. I never had problems with playing such disc and on some forum about DVD movies i read that it is normal and happens in production process. anyone can put some light on this?