The question is flaed in two senses:
Firstly, as stated, communism takes various forms, some more successful than others.
Secondly, for some people communism IS unacceptable, so the premise is wrong anyway.
As for the Soviet Union and communism, it started out as an internationalist ideal and pretty much ended up as a Russian empire. It adopted the mentality of its dominant - Russian - ethnicity.
Russians are a slave nation - they were slaves before communism, slaves during it and they're still slaves now.