A loathsome guy trips up

Once upon a time, there was a movie about a New York shark named Sidney. It was a tough, ruthless, truth-telling tale about the bottom-feeders who cling to celebrity - a tabloid classic with the sting of a Weegee photograph. You hated Sidney so much you adored him, and the movie let you. It was called "Sweet Smell of Success" (1957).

"How to Lose Friends and Alienate People" also features a swine-hero named Sidney - the homage seems overt - and does everything it can to make us detest him. It succeeds so well that we want nothing to do with the character after the first three scenes. Then the movie decides, no, wait, he's really a lovable scamp.

Sorry. Too late.

Fictionalized from a memoir by British journalist Toby Young about his brief, misbegotten career at Vanity Fair - minus the acidly self-skewering tone that made the book bearable - "How to Lose Friends" may be the most actively unpleasant movie of 2008, a status it seems alternately proud of and terrified by. Simon Pegg, the cheeky writer-star of British genre comedies like "Shaun of the Dead" and "Hot Fuzz," stars as Sidney Young, a Fleet Street enfant terrible who arrives at the Manhattan offices of Sharps magazine wearing a T-shirt with an unprintable motto. Things go downhill from there.

The magazine's editor is Clayton Harding (Jeff Bridges), who's a floppy-haired stand-in for Vanity Fair majordomo Graydon Carter (interesting given Carter's own obsession with "Sweet Smell of Success" in the old Spy magazine during the 1980s). Megan Fox plays a sex-kitten movie star; in the movie's one good joke, the character's debut role is as the young Mother Teresa. Kirsten Dunst is cast as Alison Olsen, plucky fellow journalist stuck in a dead-end affair with piggish editor Lawrence Maddox (Danny Huston, sounding more than ever like his late father, John). The problems start right there for both the movie and Dunst; Sidney's so loathsome that Alison's eventual warming to him seems patently insane.

Nothing in "How to Lose Friends" feels fresh or on target. A powerhouse publicist played by Gillian Anderson is a wan imitation of Meryl Streep's Miranda Priestley, down to the "that's all" kiss-off. The scene in which Sidney inadvertently brings a transvestite stripper to the office on Take Your Daughters to Work Day - a true incident, apparently - might have been comical but is filmed for maximum boorishness by director Robert B. Weide. Weide may be a longtime "Curb Your Enthusiasm" producer/director, but as a screenwriter, Peter Straughan is no Larry David. As a star, neither is Simon Pegg.

"How to Lose Friends" makes an interesting comparison with "Ghost Town," another movie currently trying to broaden a British comedian's American resume. Both start out nasty and end up unconvincingly nice, but at least you come out of "Ghost Town" wanting to see what Ricky Gervais will do next. The difference is wit: On the basis of their respective movies, Gervais has it. Pegg is halfway there.

Ty Burr can be reached at tburr@globe.com. For more on movies, go to www.boston.com/movienation.