I think she is a badly written character, but intentionally.
You see, her going from bad to downright insane when making fun of the young (because Scoots hasn't really grown up enough yet) isn't really character development. It's just a 'desperate times call for desperate measures' scenario. A badly written character comes off as someone we're going to dislike. I mean, let's face it, who actually likes her? I'm pretty sure her parents despise her.