Buffy, from the obvious, has always struck me as being a serious jerk. Her treatment of Spike is absolutely apalling, and while I could see why she would be hostile towards him after he tried to rape her, she was just as horrible to him beforehand. She's also clearly a racist- I mean, she kills all sorts of demons with reckless abandon, but when someone kills a human, even a totally evil bastard who doesn't have a demon's excuse of needing to kill to survive, that's suddenly crossing the line because humans have "souls?"
Which is actually a gripe I have with Buffyverse protagonists in general- if having a soul is so important and marks the difference between demons and humans, why are Angel/Angelus and Soulless/Ensouled Spike considered the same people and held accountable for each other's actions? It's explicitly stated that not having a soul removes all sense of morality and instills bloodlust, so clearly Angel wasn't in control of himself during the Angelus years. Furthermore, Angelus makes reference to being trapped in Angel's head, scrabbling at the walls, which shows that they're seperate personalities- yet Angel's whole schtick is atoning for what "he" did as Angelus, even though in a very real sense he and Angelus are entirely different people.