Yesterday, 01:01 AM
Probably not poorly "engineered" but manufacturing is an imperfect mechanical process and there can be manufacturing defects. They are not necessarily manufactured to be "bit perfect" but they should play "audibly perfect" on a CD player. As far as I know, a CD with small "data errors" is not considered defective by the manufacturer as long as it sounds OK when played.
The data-layer is on the top of a CD and it's read through the full-thickness of the polycarbonate. It can be damaged from either side and I think it's easier to damage a CD from the top, and it's not as easy to see the damage because of the label/printing, and you can't repair top-damage by polishing. (The data layer on a DVD is in the middle of a polycarbonate sandwich, so you can sandpaper the top without hurting it. The data layer on a Blu-Ray is on the bottom.)
The data-layer is on the top of a CD and it's read through the full-thickness of the polycarbonate. It can be damaged from either side and I think it's easier to damage a CD from the top, and it's not as easy to see the damage because of the label/printing, and you can't repair top-damage by polishing. (The data layer on a DVD is in the middle of a polycarbonate sandwich, so you can sandpaper the top without hurting it. The data layer on a Blu-Ray is on the bottom.)