Same probelm here! You are very lucky to have run only into a couple!!!!
I bought a TY cakebox two years ago and every CD-r was just perfect.
Bought a new TY cakebox a week ago and it was almost a disaster.
Talking about audio cd, the perfect write speed for me used to be 16x.
Now It doesn't matter the writing speed... the result can change every time: very high level of C1 error and sometime some C2 too.
Send an email to my supplier and he honestly replied me :
Since Taiyo Yuden sold by JVC, unfortunately the quality declined.
Unfortunately we have no influence on that, sorry!
Unfortunately, my test and scan can just confirmed me the TY quality is not the same it used to be... not anymore.
My guess is they just do not care... money, a low cost production and who cares about quality!
If I couple of years ago I would have said the T.Y. were the best, today I would say they are producing medias in a slapdash way.