When Francis talks to Scout he reveals an unpleasant feature of Aunt Alexandra. What is this?

Francis exposes his grandmother's (Aunt Alexandra's) racism.

“Just what I said. Grandma says it’s bad enough he lets you all run wild, but now he’s turned out a nigger-lover we’ll never be able to walk the streets of Maycomb agin. He’s ruinin‘ the family, that’s what he’s doin’.”