>>18077032It's a mannerism of hers, and one of the reasons she looks like she's "shape shifting," which in turn makes people feel uncomfortable. Pair that with her shift in attitude from a ditzy girl with a girly voice, to her serious voice with the Manson stare plus lazy eye, and you can see why it comes off as if she's a psycho.
One thing to keep in mind is that she admitted to playing a "character" for the show, and that most of her reactions were just an exaggeration. Whether or not that's true is left up to you to decide.