There are official standards for acceptable PIE, PIF and POF on a DVD. Several standards issued by ECMA for different types of DVDs list these standards, and they are:
Total PIE in any 8 consecutive ECC blocks should not be higher than 280.
Total PIF in any ECC block should not be higher than 4.
Total POF on a disc should be zero. This limit isn't written as such in the standards, but it's implied that POF are unacceptable since that means that all error correction has failed.
The standard applies to a DVD read at 1x in a drive calibrated in a certain way, and consumer drives may show error levels lower or higher than this, but usually a scan in a recent consumer drive will show lower PIE/PIF than a professionally calibrated scanning drive.
I use more or less the same standards with some additions. Normal scanning drives show PIE per 8 ECC blocks, but those are fixed 8 ECC intervals in stead of floating 8 ECC intervals, so in order to be sure that no 8 consecutive ECC blocks have more than 280 PIE, the reported PIE must be half that or lower, i.e. 140.
My standards for 8/1 ECC scanner (PIE per 8 ECC blocks, PIF per 1 ECC block):
Max PIE <= 140 , Max PIF <= 4 , Smooth Transfer Rate Tests , Jitter <= 11%
My standards for 8/8 ECC scanner:
Max PIE <= 140 , Max PIF <= 12 , Smooth Transfer Rate Tests , Jitter <= 11%
In addition to those standards I don't accept burns with PIF "clusters" of over 1000 PIF per 100 MB or so.
Just like the next person I want my PIE/PIF/Jitter as low as possible, but unlike most I care more about having acceptable scans in several drives at multiple scanning speeds than I care about having ultra-low PIE/PIF.
I would rather have a disc that can scan in my three most trusted scanning drives (Plextor, LiteOn, BenQ) at low, medium and high speeds with PIE/PIF within the limits listed above and smooth Transfer Rate Tests, than I would have a disc that scans with zero PIE (not possible) and zero PIF (highly unlikely) at low speed but showing poor quality at high speed or in another scanning drive.
Yes, you read that right! Having an outstanding scan at low/medium speed is no guarantee of having a disc that reads and scans well in other drives, so I'd rather have a disc that does well in all tests than have a disc that is outstanding in one test!