I think the 800m runner was 100%, yes.
With Marita, possibly but, and this is only my personal opinion, I did think the Americans that the East German athletes they were up against weren’t squeaky clean either. Yes, it wasn’t state organised but it still was the same effects on athletes. You could actually argue those young East German women were victims in a way too.
The other aspect though, which was nothing to do with doping, is that sports success was so important for the East German state that they put it front and centre in other ways, in terms of investment in their system. They had fabulous coaching, and process that identified talent really young in schools, for all sports, based on born natural characteristics be it wing span/arm length for throwers (or swimmers) or lung capacity etc for other events, then supported and nurtured that talent intensively.
If I’m honest too, as a kid I also suspended my disbelief, just like I do now watching cycling (or football!) because if you didn’t, you wouldn’t really enjoy much sport at all I suppose.
(One or two sportsmen & women I do still find a bit too suspicious to ignore though!)