I'm getting consistently bad write quality on some verbs i wrote. threw four of them away. one failed verify, three of them had pif errors jumping to around 5- 20 in starting, middle or end of disc. 
thinking it might be bad disk i wrote at 6x and getting pif error at 4 from starting and also around ending of disc. is my writer writing bad discs or are the media bad? the verbs are from middle of a new box i got a few months back.
Also how to check which one is at fault?

thinking it might be bad disk i wrote at 6x and getting pif error at 4 from starting and also around ending of disc. is my writer writing bad discs or are the media bad? the verbs are from middle of a new box i got a few months back.
Also how to check which one is at fault?