Soviet cartoons.

Mostly, Soviet cartoons have many flaws. Firstly, they have a boring and banal plot, a lack of hidden meaning, excessive idealism, a lack of action and emotion, unattractive animation, and are generally aimed at children. And after all that, there's a well-established stereotype among people that cartoons are for children.
In general, American cartoons of that time were comparatively better; now, most American cartoons are just utter nonsense, drawn in a notebook on someone's lap. I won't even compare them to anime – Soviet cartoons don't even come close...