It would be interesting to take cd-r recorded some years ago and use Scandisc (from Nero CD Speed) to determine the amount of damaged/unreadable sectors..
Obviously the cds should be in good conditions.

I've made some test:

CD-R FROM 2001
---------------------------------------
TDK Reflex (8x compatible)
Good: 100 %
Damaged: 0 %
Unreadable: 0 %

MMORE Black Edition (16x compatible) 700MB Macrolon
Good: 100 %
Damaged: 0%
Unreadable: 0%

MMORE (cheap) 750MB
Good: 99,8 %
Damaged: 0 %
Unreadable: 0,12 %

CD-R FROM 2000
---------------------------------------
VERBATIM Data Life Plus (4x compatible) 650MB Metal AZO UV Resistant
Good: 97,835 %
Damaged: 2,16 %
Unreadable: 0,005 %

VIVASTAR Premium Grade (12x compatible) 650MB
Good: 98.53 %
Damaged: 1.36 %
Unreadable: 0.11 %

MITSUBISHI 650MB
Good: 97.97 %
Damaged: 1.88 %
Unreadable: 0.16 %

MAXELL 74XL (8x compatible) 650MB
Good: 80.76 %
Damaged: 19.09 %
Unreadable: 0.16 %

-> All cd burned at 8x(2001) and 4x(2000)

I know isn't the best way to determine the quality of cd-r but it will be interesting. If you have other brand/older cds you can report the results.

Oh no !
You're the first one to report some Verbatim Azo decaying... You can post your list in http://forums.afterdawn.com/thread_view.cfm/3247

So far, we gathered reports of dead CDRs of the following brands.
Now that Verbatim joins the ranks, Tayo Yuden remains the only good manufacturer with no dead CDR known yet (MPO is too young for the CDRs to be dead yet).

No name made by Fornet
Samsung made by CMC
Samsung made by Seantram
No name made by Multi Media Masters & Machinery SA
Mitsui SG
Mitsui Golden Dye
Mitsui gold
Sony made by Mitsui
Kodak Gold Color
Kodak gold-bottomed (not greenish bottom)
Targa made by Lead Data
Ricoh
? made by Ritek
TDK
Koch made by ?
Traxdata made by ?
No name made by Princo
Memorex made by ?

I think the conclusion is that it's not a matter of brand, dye, or metal. All CDRs eventually become unusable after a time varying from 0 (coaster) to several years.

Heat must be an important factor. If each year the CD is exposed to 40 °C for weeks in summer, its lifespan might be shortened.

I just bought some durabrand cd's today. Now before I open the package... how do they rate?

What about the heat produced by the equipment itself which the disc is used in, and gets heated up from?

Every audio CD that gets played in my DVD player are more than warm once I eject them. This leads me to think and believe that some of the premature disc failure I've experienced was indeed heat related. Could the players which are running very hot partly take the blame and or be the cause?

I don't know. The mechanical stress when the CD is ripped at 20-40x (CAV) can also be a factor... remember that a speed of 60-120x (CAV) breaks any CD.

hehe... yeah i remember


and something else: you talk about brands, but not about manufacturers... (important, although it is hard to find info on)

In the "A made by B" statement, A is the brand, and B is the manufacturer showed by the ATIP.
Mitsui, Kodak, and Ricoh are direct manufacturers.