It’s really sad about Eddie Murphy. Here he gets nominated for an Oscar (and deservedly so, one could argue) for “Dreamgirls” — and then people will see “Norbit” and not vote for him purely out of spite. Surely the man responsible for this appalling disaster doesn’t deserve an Academy Award for ANYTHING, they’ll reason.

They may have a point. “Norbit” reminds us that “Dreamgirls” was a fluke for Murphy — not in terms of his performance, which is typically laudable, but in terms of his choice of material, which (apart from the mostly harmless family flicks) has been questionable for most of his career. “I Spy”? “The Adventures of Pluto Nash”? “Showtime”? “Life”? “Holy Man”? “Vampire in Brooklyn”? When it comes to spectacularly unfunny comedy, the supposedly very funny Eddie Murphy sure knows how to pick ’em.

He and his brother Charles conceived the story, with the actual writing credited to Jay Scherick and David Ronn, the duo behind such unpleasantries as “National Security,” “I Spy,” and “Serving Sara.” To ensure the film’s failure, Brian Robbins was brought on board as director. You may know his work: “Varsity Blues,” “Hardball,” “The Perfect Score,” and last year’s “Shaggy Dog” remake, to name a few. He’s a bad director who makes bad movies. And so, with the lame premise, the dull script, and the untalented director all in place, “Norbit” was ready for action!!

Eddie Murphy returns to his “Nutty Professor” shtick, playing three roles: Norbit, a quiet nerd; Mr. Wong, the Chinese man who runs the orphanage where Norbit grew up; and Rasputia, the obese, domineering woman who has bullied Norbit into marrying her. They live in a small Tennessee town, where Rasputia’s thuggish brothers comprise the local mafia, and where everyone knows and pities poor Norbit.

Norbit is resigned to his sad lot in life until he runs into Kate (Thandie Newton), his childhood girlfriend who’s now all grown up … and engaged. Her fiance is Deion (Cuba Gooding Jr., speaking of Oscar winners who embarrass us), who, in the film’s lazy shorthand, is required to be a gold-digging scoundrel. Why? Because otherwise there might be, like, a DILEMMA when Kate eventually dumps him for Norbit (which of course is the film’s only possible outcome).

Back to Rasputia, though. Yes, she’s hugely fat and thus ripe for ridicule; Murphy is hardly the first comedian to dress up like a fat lady and stomp around for the sake of comedy. (For that matter, it’s not even the first time Murphy himself has done it.) But Rasputia isn’t just fat: She’s also a total beeyotch, as the kids say, jealous, controlling, mean-spirited, and vicious — oh, and unfaithful, which is necessary because it justifies Norbit’s eventual infidelity to her.

The few times I laughed during the film (and it was very few), it was because of Rasputia. Some of the sight gags involving her girth are funny, aided in no small part by the amazing special-effects work of the legendary Rick Baker. (Further, while Robbins may be incompetent as a director, at least he had smart FX advisers on this project: The scenes involving multiple Murphys are astonishingly well done from a technical standpoint.) Murphy’s portrayal of the shrill harpie is occasionally so outsize and repulsive that it’s hard not to be amused by her ghetto-rat cluelessness, as when she squeezes herself into her tiny car and, every time, accuses Norbit of moving the seat up as an explanation for why she can’t fit.

Then again, the character is still troubling. She’s irredeemable. She’s not a horrible person whose horribleness is explained by her low self-esteem, or by the cruel taunts she suffered as a child, or by a chemical imbalance. She’s just a nasty human being, end of story. But where’s the sport in mocking a creature such as that? From a comedic standpoint, it’s too easy. From a storytelling standpoint, it’s too lazy. Even the Wicked Witch of the West had some motivation for her evil (the whole house-on-my-sister thing) — and she was an actual WITCH! Rasputia is supposed to exist in the real world.

As for Norbit, Murphy’s task was nearly impossible. It’s hard to carry a movie in which you spend the whole time making a “funny” face and doing a “funny” voice. With his grimacing smile and inexplicable New York accent, Norbit would be fine in a five-minute sketch — but not as the central character in a movie. You can’t be a fully realized, three-dimensional character when you’re doing this kind of clowning, and you can’t expect people to be interested in your character’s problems if he’s not a fully realized, three-dimensional character. Moreover, Norbit is the straightman in the film — the gentle figure around whom the insanity takes place — yet Murphy plays him big, as if he’s supposed to be getting laughs.

Some of these shortcomings would be irrelevant if the movie were funny, of course; funny covers a multitude of sins. But it isn’t funny, and these fatal flaws in the story, premise, and execution are part of the reason. The cast members who are not Eddie Murphy (including Terry Crews, Eddie Griffin, and Marlon Wayans as various pimps and reprobates) are left to flounder, with no material and no direction to save them from the awfulness that surrounds them. Timing is everything in comedy, and releasing “Norbit” into theaters at a moment when people are beginning to respect Eddie Murphy again is an example of some seriously screwed-up timing.

D- (1 hr., 42 min.; PG-13, some sexual dialogue, a lot of vulgarity and crude language, some profanity.)