From my personal experience, all cheap/fake CD-R and DVD-R I’ve lost were without any visible signs. They wouldn’t be recognized by the drive or not all the data could be extracted. When scanned (if it was possible) they showed enormous number of PIE and PIF errors.
So far I have seen only two discs that had visible signs of failing - one DVD-R from Optodisc (12 years old from 8X era) that has dye discoloration in form of circles at the outer edge and one CD-R from TY (Verbatim Pastel branded) that has few fingerprint like pattern on the dye (I suspect that someone touched the substrate in the factory before the dye was spread).
I still haven’t noticed any problems with my factory pressed discs so I can’t comment on that subject.