I was looking at people complaining about bad media only to find it was their FW that was the issue. One way to quickly tell if the media really is bad is to have 2 or more rewriters. Now I am not saying this is always practical. But it's a good idea nonetheless considering how cheap the burners are these days. Preferably have at least 1 of the drives with scanning capability.
Burning on a second drive gives a general indication if the media is bad or the drive/FW is bad I have found. I was having trouble with some Fuji TY media on a NEC 3540. Yet my Lite-on and Benq love them.
Saves you wasting batches of discs too. Just burn a second disc on another drive and compare.
This might seem an obvious idea but I thought I'd make it prominent