Ritek DVD-R flakey?

I'm cleaning up my file library and I just came across a Ritek DVD-R that
looks fine according to the directory structure, but about 80% of the files
I read from it are coming up as all zeros.

I copied the contents of the disk to my hard drive without errors. All the
files that I expect to find on the disk are there, but most are just zeros.

Manufacturer ID is RITEKG05.

Google seems to be confirming the crappy quality of these disks. They all
burned great and worked for several months without any problems.

So, how does one KNOW that they are getting good quality media? Even trying
to buy brand name, like Taiyo Yuden, you could end up with fakes.