After reading a lot of horror stories how people lost backups stored on burned CDs or DVDs that were only few years old I decided to check in what state was my own optical media collection. To my surprise even the media that was considered 2nd and 3rd grade quality (CMC Magnetics, Optodisc, Princo) was perfectly readable on every DVD reader I own (except few exceptions of mistreated media). Later I decided to look for the oldest media I own (of every manufacturer) and do some quality scans using Nero DiscSpeed. I will post those scans on this thread.
To everyone interested in this topic feel free to contribute with comments and your own disc quality scans.