I picked up a spindle of Plextor (TY) silver inkjet printable CDs a while ago. These look really cool after printing and have been good quality.
However, one of them scanned with 3x as many C2s as C1s in KProbe. I had a closer look and saw what looks like an "unburned" patch on the dye side. I'm attaching part of a scan (with my flatbed scanner) to indicate the problem.
I don't think it's from my fatty fingers (although I did eat some pop corn that evening- but I won't bother trying to reproduce this), so I'm assuming a dye defect ...
The interesting thing is that most of the defect doesn't seem to affect the readabilty of the disc- just the wider part trailing to the left near the center seems to be the source of the C2s. The interleaving apparently allows the error correction to cope with the radial part of the mark!