Comics are a reflection of their author’s perceptions of society and therefore, if an author either buys into a pre-conceived (inaccurate) idea of what a race acts like then it would be hard to create a well rounded character of the misrepresented ethnicity. The original Black superhero Black Panther was the King of an advanced African nation that had been unspoiled by imperialism. I don’t think Stan Lee would have known how to write a liberated African American character in the 1960’s because with segregation he could do very little research and had very little firsthand experience. It’s hard to get to know someone you aren’t allowed to talk to and if you’re only looking at them from afar the lines will be blurry. Lee took the easy route by making his Black character removed from the American experience. The tribal lifestyle and rituals that dictate Black Panthers life can be seen as either interesting, or generalized but their infrequency in our world makes them a good idea for a super hero.
Comics can of course be accurate, especially in regard to the racial experiences when the author has a thorough grasp of what it means to have that background. Accuracy is important, but more important is creating a well rounded character; the less one dimensional a character is, the less they can fit into any one niche of a stereotype. The most important barrier (arguably) is adding black onlookers to the background of marvel stories. By creating an interracial background the stories were no longer in a pristine racial cleansed environment, but a form of the real world, and that gave African American characters a realistic chance to introduce themselves.