Though it features a clever Shyamalan-like twist and boasts a fresh, winsome romantic heroine in Brittany Murphy, ‘‘Little Black Book’’ is ultimately the sort of generic comedy product that turns to flatulent dog jokes when the laughs fall short, which they often do. For more sophisticated audiences, there's also a revolutionary bit involving gynecological stirrups.

The movie's unfunniness creeps up on you like a mild but inexplicable skin rash. The opening minutes are particularly flat, involving an ungainly mass of back story crudely shoveled onto the screen by journeyman director Nick Hurran (‘‘Girls Night’’).

Ambitious Jersey twentysomething Stacy (‘‘8 Mile’’ star Murphy) dumps her college boyfriend, toils for a few years in professional obscurity, finds a new, handsomer boyfriend (Ron Livingston from ‘‘Office Space’’) and finally lands a gig as a production slave for a gone-to- seed reality talk show host (Kathy Bates). Stacy also likes to warble Carly Simon songs in her most vulnerable, stressed-out moments, a trait inherited from her schizo, single mother (Sharon Lawrence).

Before you can say ‘‘You're So Vain,’’ Stacy is abusing the privileges of her new job to conduct a clandestine fact- finding campaign against her boyfriend's ex-girlfriends, whom she looks up in his electronic planner.

Egged on by a cynical colleague (Holly Hunter), Stacy arranges off-camera interviews with the women on bogus topics and even becomes unlikely friends with one, a freckle-faced chef played by the always-appealing Julianne Nicholson (‘‘The Love Letter’’), who looks a bit like Howdy Doody's taller, very datable, older sister.

It comes as no surprise when Stacy's devious plottings bite her on the derriere, but the sneaky, singular manner in which they do speaks volumes about the carnivorous nature of talk show television and proves to be the one saving grace of an otherwise punchless script by Melissa Carter and Elisa Bell.

Hunter, playing a jaded, corrupted version of her character in ‘‘Broadcast News’’ (1987), is a bit over-articulated as Stacy's Machiavellian pal, but Murphy strikes a nice balance of ditziness and warmth as Stacy, proving that she can stow some of the edge (the skankiness of ‘‘8 Mile,’’ the dementia of ‘‘Don't Say a Word’’) and still remain an active and interesting screen presence.

On the subject of romance, ‘‘Little Black Book’’ is worse than pointless — it champions the diseased notion that total transparency is a healthy thing. Stacy's bad behavior is ultimately justified and the movie, consequently, becomes apologia ripped straight from the pages of “Cosmo,” where spying on your loved one is a natural dimension of any dating experience.