Blu-ray issues, how do you know its a defective disc versus it being the transfer?

[beware]

Just like the title suggests, when an issue happens on a bluray disc, short of freezing or heavily pixelating, how do you determine the cause?

I only ask because I recently upgrading my dvd to bluray of Batman Begins, and the black levels in that movie absolutely suck! It got annoying when you would sorta see "stripes" on one side of it being a darker black and then lighter. So much so I exchanged it thinking it was the disc but the replacement had the same issue.

So, its the transfer.

I also read about how that transfer is short of amazing, since its truly 720p and it looks quite fuzzy at times...

But also like with the Die Hard collection I got.

https://forum.blu-ray.com/blu-ray-mo...-2-bluray.html

Die Hard 2 had these issues and it seems as if the "rip" is a transfer thing. I still don't know about the hair thing, but I am pretty confident its also from the transfer. I know films being up converted from the 80s aren't going to be the best quality, maybe I just have too high expectations of bluray technology...

Who knows...

Should I just chalk the Die Hard 2 issue up to the transfer? I mean it played all the way through just fine, just those 2 quick issues...