You know why vhs quality degraded with every generation of copy? It wasn't an accident or a technical problem, it was deliberate.
They want to discourge people from copying their tapes, so there was a mechanism in the VCR to actually cause some drop in quality when you taped something.
This is why TV tapings of a movie would never be as good as buying/renting the same movie from a store. Even if you used a virgin tape.