From Scary Movie to, well, Scary Movie 4, you'd have to look long and hard to find a talented comedienne with a spottier resume than Anna Faris's. This is a truly horrible shame, since even in the trashiest trash, the actress herself is never less than completely charming and endearing, and in those few cases where she's chanced her way into a small role in an actually great film, like Lost in Translation or Brokeback Mountain, she's stolen every one of her scenes.

And now, she's got her first bona fide starring role with the Happy Madison production of The House Bunny, a slightly worse than routine comedy with a sharp sexist edge, which if it does nothing else useful should at least demonstrate that Faris exists, and can carry a whole movie all by herself. So hopefully in a couple of years this will trickle down into a couple screenplays written just for the actress that play to her strengths without being completely insulting.

In the meantime, this is what we get: the latest in the long line of "Let's save the frat house!" Animal House knock-offs, whose theme is best boiled down to this: remember girls, it's good to be smart but it's really important to be pretty. Faris plays Shelley, an orphan who was adopted into the Playboy Mansion family of Bunnies at the age of 18 and has grown into something like a den mother for all the little Bunnies by the time we meet her, about a week before her 27th birthday. Thanks to a jealous colleague, Shelley is forced from the Mansion on the pretext that all Bunnies are let go at age 27 (Hef apparently enjoys Logan's Run), and she eventually finds herself at the doors of Zeta Alpha Zeta, the least popular sorority at an unnamed California university. The Zeta girls have coincidentally just been told that if they can't manage 30 pledges pronto, they're going to be kicked out, and Shelley takes it upon herself to teach the seven remaining members of the sorority all about the fine art of impressing girls via impressing boys.

This goes exactly where you'd expect: a montage by which extremely pretty starlets (including Emma Stone of Superbad, former American Idol contestant Katharine McPhee, and Cheetah Girl Kiely Williams) learn that with a tiny amount of makeup and clothes that don't come from Goodwill, even an extremely pretty girl can look fucking gorgeous - and of course, at least a couple of them look nicer and more distinctive in their "ugly" garb, though maybe I just have a thing for girls with piercings. Moreover, they eventually figure out that looking like cookie-cutter bombshells is no way to go through life with dignity, and so they figure out a way to look like cookie-cutter bombshells with personalised hair styles.

As for Shelley, she goes and falls for Oliver (Colin Hanks), the manager of a nursing home, who doesn't fall for any of her porny seduction tricks, and so she attempts to become super-smart to impress him, before coming to the conclusion that it's best just to be whoever you are inside, and if they don't like it, they can go to hell. It's in the grand tradition of Happy Madison Productions that some minor attempt should be made to carve a socially redemptive message out of a film whose comedy all derives from the exact opposite of that message, but at least The House Bunny makes a better stab at it than, oh, I Now Pronounce You Chuck and Larry. Still, for the great bulk of the film anything redeeming is far on the back-burner, as pornstar femininity is held up for our approval (the Playboy Mansion seems about as naughty as a McDonald's playland in this iteration). The fact that two women, Karen McCullah Lutz and Kirsten Smith, wrote this (theirs is also Legally Blonde) frustrates me to no end. I expect it doesn't need saying that most of the gags die in the instant they're told; largely because only the most sheltered viewer hasn't seen them a dozen or more times.

Into this mess walks Faris, and my God but she turns a sow's ear into a silk purse. It would be too much to ask that she makes it a great comedy; but there are several places where she does a something, je ne sais quois, that makes a line that couldn't possibly work on paper into something which is at least funnyesque, if not quite hilarious (she even turns a dire running gag, in which Shelley remembers names by repeating them in a guttural growl the moment she learns them, into a consistent laugh-getter). And better even than that, she almost manages to make the cynical attempt at Good Morals work; she actually makes us feel for this cardboard Dumb Blonde, and make Shelley's attempts to be more than just a Bunny seem both real and touching. The scene where she realises that all her tricks aren't enough to snare Oliver, that properly grown-up men need more than just sexy theatrics to keep their interest, is a a quietly tragic moment that calls to mind no less than Marilyn Monroe, the cinema's poster girl for seeming airheads with a hidden measure of pain deep inside.

I write that, and I don't even know if I believe it: does a movie as resolutely worthless as The House Bunny actually manage to reveal that we have our very own modern-day version of Marilyn? I almost don't want it to be true, but there's Faris, suggesting otherwise. I'm officially putting her on watch: she has two years to do something worthy of her talents, and then I'll call her one of the great contemporary comediennes. In the mean time, let's just marvel that she gives one of the best performances of the year thus far in a movie that never comes within swiping distance of deserving it.