Arguably, the overall theme of Aunt Alexandra is one of disapproval. She cannot stomach the way that Atticus is raising his children, particularly the way he is raising Scout. She feels he is far too liberal, far too permissive, and doesn't do enough to teach the children about their background and how they ought to act.
It is a consistent part of Aunt Alexandra's character that she tends to look down on others. At times, for example when she is meeting with her missionary friends, she wants to try to help people and considers her station one from which she can reach down to lift people up.
But more often, she is trying to maintain a sort of status and position for the Finches as an old and respected family in Maycomb County. As such she is desperate to fix the way she dresses, the way she talks, the way she eats, even the way she interacts with other people. Her disapproval is constant and vigorous but she does take breaks every so often to be genuinely nice and caring.