In theaters

THE SWEETEST THING. Directed by Roger Kumble. Written by Nancy Pimental. 84 minutes. Rated R.

The thing about Roger Kumble’s “The Sweetest Thing,” a raunchy sex comedy about a trio of trollops living the low life loosely in San Francisco, is that it wants to be a cross between “There’s Something About Mary,” “Charlie’s Angles” and “My Best Friend’s Wedding.”

But in spite of featuring Cameron Diaz – the co-star of all three of those films – in the lead, “The Sweetest Thing” is too cynical to be cute, too dirty to be endearing and too dumb to offer anything more than a few isolated laughs.

The film, from a script by “South Park” writer Nancy Pimental, exaggerates the elements that made its predecessors work, particularly the gross-out scenes in “Mary,” which now, after years of copycats determined to outdo one another, seem more like the stuff of Romper Room than ever.

Like so many other filmmakers who missed what made “Mary” work, Kumble and Pimental believe that the more insanely crude they are, the funnier their movie will be, which isn’t the case, as anyone who saw “Say It Isn’t So” and “Freddy Got Fingered” can attest.

Still, they’re insistent that this is the case, and thus treat audiences to a whole host of “shocking moments” – a semen-stained dress, a horrific moment of lockjaw and oral piercings gone awry, a breast implant fiasco – which their stars, Diaz, Christina Applegate and Selma Blair, are only too happy to indulge them in.

In the film, these particular angles – Diaz as Christina Walters, Applegate as Courtney Rockliffe and Blaire as Jane Burns – aren’t seeking Mr. Right as much as they’re seeking Mr. Right Now. But when Peter Donahue (Thomas Jane) steps into Christina’s life, all of that changes as she realizes, on the basis of one cocktail, I might add, that this realtor is Mr. Forever.

If “The Sweetest Thing” had taken its inspiration from HBO’s “Sex in the City,” what ensues could have been insightful and fun. But since somebody here is secretly planning to wed while most of the others are secretly engaging in experimental sex, what actually occurs is not unlike “My Best Friend’s Wedding” as directed by Larry Flynt.

Grade: D+

On video and DVD

THE DEEP END. Written and directed by Scott McGehee and David Siegel. 99 minutes. Rated R.

In “The Deep End,” Scott McGehee and David Siegel’s riveting, noirish thriller based on Elisabeth Sanxay Holding’s 1947 novel, “The Blank Wall,” and, in turn, Max Ophuls’ 1949 movie, “The Reckless Moment,” a mother’s love for her son is tested and proved in what’s easily one of the best films Hollywood put out last year.

In the film, Scottish actress Tilda Swinton is Margaret Hall, a Lake Tahoe mother trying her best to balance a busy home life, one that includes three self-involved children, an ill father-in-law, a Navy husband who’s never home, and a corpse that’s recently washed up in front of her swanky lakefront home.

Margaret knows the corpse all too well – it’s Darby Reese (Josh Lucas), the seedy owner of a gay nightclub called The Deep End who’s been having an affair with her 17-year-old son, Beau (Jonathan Tucker).

Convinced Beau is somehow behind Reese’s death, Margaret launches into action to protect her son. Secretly, and with a soccer-mom’s efficiency, she slings Reese’s body into a boat, drops it into the lake, ditches his car, and hopes that will be the end of it.

Of course, it isn’t. When a dark, dangerous stranger named Alex (Goran Visnjic) threatens her with a salacious videotape of Beau having sex with Reese just as Reese’s body is being hauled out of Tahoe by authorities, it becomes clear that Margaret will have to go to unusual depths of her own to keep the illusion of her family together while privately fighting to keep her son away from a life behind bars.

The result is seductive, rich and atmospheric, a gorgeously shot and acted movie that recalls the best elements of Chandler and Hitchcock. The reason it resonates so deeply on an emotional level is because of Swinton’s terrific performance. Just beneath her cool facade is the worry of every mother’s nightmare: her child and his future are in danger. When Margaret fully realizes this, there is nothing that can stop her from protecting him.

Grade: A

Christopher Smith’s reviews appear Mondays and Fridays in Style, occasionally on Fridays on E! Entertainment’s “E! News Weekend,” Tuesdays on “NEWS CENTER at 5” and Thursdays on “NEWS CENTER at 5:30” on WLBZ-2 and WCSH-6. He can be reached at BDNFilm1@aol.com.