1) Is it possible for DVD Decryptor to create a bad iso without me knowing?

I am asking this because I am using DVD-X-Copy to split episode DVDs. I am first buring to DVD+RW, then creating an ISO from than, testing that ISO then burning to DVD-R. This is faster than rerunning DVD-X-Copy as the program erases everything after each burn.

The DVD+RWs I am using have seen a quite a bit of use and have scratches and whatnot. So I want to know if it is possible that for data to be lost when I am writing to and reading from the DVD+RW. Does the UDF file system support some sort of error detection or checksum that would alert me to such problem?

2) Is it possible to write a DVD, have all the files and folders a perfect bit for bit copy (I use SFV to test this against the .iso whenever I burn) and still have a bad copy. What I mean is can there be a problem with the way the files are actually stored with will result in slow playback or skipps?

I ask this because at some forum someone was using some benchmark utility to create a graph of the DVD read speed across the entire DVD.

The person was saying that he knew the media/burning method was sound because the graph had no irregularities.

3) If it is possible to have a bit for bit recording with performance issues,

a) what causes such problems (burn proof?),
b) how can I detect them, and
c) will they propogate when such problem discs are again copies (DVD+RW to DVD-R for instance)?