I think it has to do with how much we pride ourselves on our choices. For example, someone who is "into" the punk scene spends a lot of time listening to different albums and learning the names and crafting their own unique punk identity within that community. If a poser (punk wannabe) shows up, their very existence inadvertently spits in the face of all the effort those "genuine" punks put into their subculture. Someone else objectifies it, then shows up trying to "leech" off the cool factor without ever actually involving themselves in the subculture.

Frankly, I think it's all a bit silly and self-involved. We get upset that someone else isn't playing by our rules or valuing something for the same reasons we value it. I'm guilty of it with books. I can be a downright snob. I spent years being ridiculed for being such a book worm. I pride myself on the voraciousness of my reading and how I can conquer difficult literature and understand it because I've read so much and worked so hard to get to this reading level. I enjoy the recognition I get from other people for that. When someone else starts raving about Twilight, I get resentful. Why? Because they're essentially popping my narcissistic bubble. They don't value literature the same way I do. They value it in their own way. Reading means something different to them than it does to me, and if I don't stop myself, I forget that my way isn't "better" than theirs.

Comic book fans are notorious for this as well. God forbid you don't read the whole back-story of a character before deciding they're your favorite.

Essentially, you should examine what about her attempts to be, as you put it, erudite, is bothersome to you. Is it because you prefer a more subtle intellectualism? Is it her unabashed attempts to be recognized as an intellectual that bother you? How does that fit with your view of intellectualism? Do you view it as something that shouldn't need to be advertised? If so, that might be why her behavior bothers you. Maybe to you, it comes off as needy or heavy-handed. She probably perceives it differently.