There's a theory in modern film criticism (and especially the type of modern film criticism popularized on my much-beloved blogs like Cinematical. com and TheAvClub.com) about the Manic Pixie Dream Girl. The MPDG can basically be summed up as a semi-insane (read also: quriky!) girl whose main purpose in the film (and in life) is too brighten up the dreary life of the male protagonist. She tap dances along the line between adorable and annoying. Examples, at least examples purported by those blogs, are Kirsten Dunst in Elizabethtown and Natalie Portman in Garden State. Not an example? Kate Winslet in Eternal Sunshine, since she's actually got an inner life of her own. In fact Winslet can be seen as a deconstruction of the MPDG myth, in that she says that guys always expect her to save them, but she's just a fucked up girl in her own right.
Anyway, to better understand the phenomenon that is MPDG's, check out the source article at the The AV Club. I don't neccesarily agree with all of their choices, but it'll give you a good basis for comparison with my new theory.
Back to Adventureland. As I left the theater, one issue kept sticking in my craw*: Kristen Stewart. It's not just that her character in this is basically Bella without the vampires, it's that she's the type of doe-eyed ingenue that mostly male screenwriters create to indulge in a little saviour complex. She's basically the opposite of MPDG - she's the Depressed Long Haired Dream Girl (DLHDG), which doesn't roll off the tongue quite as easily. She has an inner life in that she's "depressed." We can tell this because she makes bad decisions and has dark eyes. But her depression is never anything more or less than a prop to the male protagonists angst. She's more often than not played by an actress who isn't asked to do anything more or less than look down, sadly, and whose not particularly charismatic in her own right. We're meant to believe she's smart enough and interesting enough for our protagonist mainly because she's depressed (which must be a sign of her rich inner life, right?), and she's almost always more sexually advanced than our male protagonist, who is simultaneously awed and scared of her sexuality.
Like MPDGs, DLHDGs have been used quite often throughout films very, very well (I doubt even the most ardent-hater of MPDGs wishes that Breakfast at Tiffany's were different) and I don't think the mere existance of one within a movie constitutes its failure (in fact, Stewart's DLHDG-ness doesn't come close to ruining Adventureland), but it is definitely as pervasive and annoying a device in films as the MPDG, Magical Negro, or Wise Cracking Grandma.
some examples (and feel free to add your own):
Kristen Stewart herself in either Into the Wild or In The Land of Women, where she plays momentary salvation girl to both Emile Hirsch and Adam Brody.
And the woman who Stewart is set to dethrone as the queen of DLHDG:
Pretty much Any Character Played By Jena Malone outside of Saved- in The United States of Leland, she was Becky Pollard. In Dangerous Live of Altar Boys, she was Margie Flynn. In Life As a House, she was Alyssa Beck. And in Donnie Darko, she was the ultimate DLHDG, the confused, tragic Gretchen Ross. For a brief period in the early 2000s, Malone defined the DLHDG.