I know a few people like that. It's not always their fault -- there's a lot of pressure put on their shoulders to act or be a certain way so they do it, heedless of how it makes them look.

[ She's thinking Slytherins, here, really, and how they had all seemed rather arrogant and awfully nasty but, in the end, they'd all been good; so many of Slytherin house had fought in the Battle of Hogwarts, though. ]