Quality before and after DDR?

I just read a story from England writen by a 301 Saxon owner, the bike was made 1994, at that time it was called MuZ. And what i could understand in the articel did the motorcycle have small problems all the time. Always something that broke or faulted. I have one TS250/1 -1977 and one ETZ251 -1989......will they also be unreliable etc......i thought MZ made i DDR was good quality...is it? Worth to be noticed is that the guy did all the required services etc. and so do I. Ofcourse a badly maintained motorcycle cant work well, so thats in not the reason in this case. 
