In Hidden Figures, we learn about the role of black mathematicians in NASA missions. We also learn of the difficulties that these people faced in the workplace. We learn that they faced discrimination and racism on a regular basis, and had to learn how to deal with it.
One of the ways in which they did so was by trying to be extremely likeable. They believed that their interactions with white people had an effect on the whole black community, and because of this, they wanted to ensure that their representation of "blackness" was a positive one. Therefore, they made a special effort to be well-dressed, well-spoken, patriotic, and upright. They also thought that this might help them avoid conflict.