The fangirls who think they know everything annoy those fangirls who do.
I'm planning to rant about how the economy is going to hell and we're all screwed and stuff, but right now I need to tackle a completely different topic: fangirls.
I'm one of those fangirls who actually analyzes the book/movie/TV show/marching band/toaster over/video game I get obsessed with. I try to figure things out and form hypotheses about what might happen next, but I will openly admit that I have been wrong on more than one occasion, and I do not think my ideas are the only ones that could ever work. I've come across many theories that are much better than mine and I've realized that some of mine are completely stupid. And once I came across on a forum as really snobby when I didn't mean to and I still feel a bit bad about that.
Also, when I first enter a forum, I try to introduce myself (by my penname, of course) and say how long I've been in the fandom (usually not very long, and I try to defer to people who've been in the fandom longer). Then I introduce my opinions and ideas and hope someone responds.
So it really annoys me when a fangirl just pops up on a forum with no introduction or anything and seems to present their ideas in a manner that feels like they think their ideas are superior to everyone else's. They propose theories that make barely any sense and seem formulated in thirty seconds, and then they spend the rest of the time jibbering about how hot Jensen Ackles/Jared Padalecki/David Tennant/David Boreanaz/John Barrowman/James Marsters/Zachary Quinto/Milo Ventimiglia/Sendhil Ramamurthy/[insert hot guy's name here] is. And it feels like they just want to jump in with the rest of the group, but they never manage to do so.
In a Supernatural forum on ff.net that has since been deleted (which is sad, because it was really cool otherwise), there was this one fangirl who did that after every episode aired last year. After the finale, she said that one of the reasons Dean could never come back as a demon was because "I would hate it." Never mind that it would've been a cool plot and that Jensen did a great job as Possessed!Doppleganger!Dean in "Dream a Little Dream of Me." This gal claimed that the actor is essentially blind when wearing those black contacts and listed a couple more cons, but she kept coming back to gushing about Jensen's "beautiful green eyes." As someone who has his black and white picture as her default icon, I'll say that she's not wrong about Jensen's eyes, but there's so much more to talk about plotwise, and most of the other posters cared more about the plot.
I'm seeing it again in a Sylar-related forum (different person, though), but it's not nearly that obnoxious. Yet.