With the Soviet cameras, you're sort of looking for a sweet spot regarding age. Cameras that aren't old enough to be decrepit, but were made before quality took a nose-dive over there. With the LTM Leicas, they're all pretty much decrepit now unless recently serviced (in fact some of them have been too well cared for and are sluggish/gummed up from lack of use).
My experiences with 70's and later Soviet cameras has indeed been bad, but the 1960's Zorki and Fed I have, have never let me down. Indeed the quality of these cameras from this era compares favorably with those consumer-grade cameras made in Japan during the same era. And I write this as somebody who has repaired quite a few vintage cameras.