As [I]Arachne[/I] & [I]kg_evilboy[/I] have already said, there is nothing inherently wrong with modern CMC CD-R. The dye seems to be stable enough & the construction sound. I can’t recall ever experiencing a failed write (coaster), and the discs I wrote 5-7 years ago are still perfectly readable & show no sign of oxidation around the edges.
But the quality of their discs varies a lot and is largely brand dependent. Certain brands earned a reputation for consistently selling poor quality ‘defective’ grade discs which failed inspection at the factory. The store own brands are probably a lottery, but TDK etc. [I]should [/I]be good discs. Avoid all defective-grade brands on principal (E-Net etc.).
Here is a recent scan of a CMC CD-R. A few years ago I received 600 Datasafe CMC CD-R in error (not the discs I ordered, refunded). Despite being an E-Net brand (:Z:Z) they have been consistently good & make great everyday/semi-disposible discs. But this isn’t the sort of quality we’re used to from E-Net and I would still recommend avoiding them completely - I guess the quality control department had an off day and accidentally let these slip through. ;)
The polycarbonate platter seems to be noticably thinner that other CD-R, presumably a cost-cutting measure (must get my micrometer out & measure them properly). The hub is thicker to maintain the correct laser to disc height. I wonder if CMC have a separate cheap disc line, or are they all like this now?
I’ve still got a single unbranded CMC Magnetics cyanine CD-R with a gold reflective layer written 14-15 years ago, and so far it shows no signs of degredation. It is still readable & scans beautifully, if you ignore an E22 spike where a piece of the reflective layer flaked off (when the disc was new). The bonding of the reflective layer is rather poor and there appears to be no protective lacquer. But even where the dye is exposed to the air there is no visible degredation.