German vinyl quality is excellent.
Usually though the record company would send a copy of the master tape to Germany to be mastered to vinyl. Sometimes this would be a second or third, or worse generation tape.
American vinyl of the time - the late '60's and '70s was generally crap. But usually mastered from the first generation tapes. So it was a toss up, what you lost on the generations, you made up for by getting on better vinyl.
Where you really get lucky is where the US record company sent the US metal matrix masters to Germany to be pressed locally. That, quite frankly is as good as it gets, period.
A couple of examples are;
Exile on Main Street
Slow Train Coming (Dutch vinyl)
and most of Bob Dylans Columbia stuff. If you look carefully.
All these records though were also mastered locally using tape copies and local engineers. So it's not so easy - you gotta' know your matrix numbers!!!
But you get a copy of "Exile" mastered at Artisan in California, or Sticky Fingers, mastered by Bob Sax at The Mastering Lab, pressed to nice thick, high quality german vinyl, you might not know why, but you know, you feel you got something special. Cos it just sounds better than any other you've ever heard.
However, all these