After 17 years of winning over moviegoers with her mile-long legs, breezy confidence and wide, almost goofy smile, one of Hollywood’s consummate charmers has had enough. Cut the charisma and cue the contempt: It’s time, finally, to loathe Cameron Diaz.

As an unrepentant moral scourge in her new film “Bad Teacher,” Diaz plays Elizabeth Halsey ― an educator who steals, cheats, lies, sleeps in class, smokes pot in the school parking lot and swears like a trucker, often in red pen remarks scrawled on the work of her middle-school students. Dumped by her sugar daddy, Elizabeth’s goal is to make enough money for a pair of breast implants that she thinks will help earn her the affections of another meal ticket, a teacher with a trust fund (Justin Timberlake) who’s as mild as she is wild.

Thirty pages into reading the script, Diaz says she thought she’d pass on the role. Instead, she made a conscious decision to try something new.

“I’m trained as an actor to look for a character to be someone at the end who people like. Reading this script, I was thinking, there’s no way out of this for this girl,” Diaz says, twirling her hair and sipping a soy milk latte at a Beverly Hills restaurant. “She does so many things that are so selfish and narcissistic and closed off. How can she be redeemed?”

In person Diaz, 38, is perky but guarded, and fond of the word “amazing.” The script? Amazing. Her costars? Amazing. The set? Amazing. That soy milk latte? Also apparently pretty darn good. But the indefatigably cheerful actress confesses she found a certain liberation in Elizabeth’s dismal disposition.

“Her disdain for life is one that I relished playing,” Diaz says. “I’m such a cheerleader, it’s kind of fun to play a character who thinks everything sucks.”

And then, you realize, she’s doing it again: Playing rotten and R-rated, Diaz may make us like her even more. Which is exactly what “Bad Teacher” director Jake Kasdan had in mind.

“She’s probably the only actress of her generation that people are actually excited to see behave this badly,” Kasdan says. “It’s part of her relationship with the audience at this point that she is this gorgeous woman who can do raunchy. Cameron appeals to both genders in a very real way. People just want to hang out with her.”

A native of San Diego and a teenage model, Diaz came to fame in Hollywood in the 1990s playing sexy but wide-eyed characters. At 21, she stepped into the first scene of “The Mask” in a slinky red dress, providing Jim Carrey with an excuse to stammer and gape and elevating the stock hot-girl role enough to earn herself a string of indie film parts.

As the high school crush who got away from Ben Stiller in “There’s Something About Mary” in 1998, Diaz was the naive center of a gross-out comedy that helped pave the way for lowbrow franchises like “The Hangover” and “American Pie.” In the movie’s most famous scene, Mary mistakes a bodily fluid for hair gel.

“Mary, the character, the movie, was sort of innocent,” Diaz said. “But Elizabeth is definitely a different kind of woman than existed in the ‘90s. She’s driven in a different way. Comedy is always a reflection of what we can laugh at about ourselves. Humor is really just people telling the truth. It just depends what truth needs to be told at that time.”

Now is the time, it seems, for leading ladies who are in on the joke. “Bad Teacher” comes on the heels of “Bridesmaids,” the Kristen Wiig movie that has earned $124 million at the box office and proved that audiences will turn out for an R-rated comedy driven by a band of mischievous females. Another test of the nascent genre will arrive in September with Anna Faris’ “What’s Your Number?” about a frisky young woman wondering just how many men she can get away with bedding.

“Bad Teacher” was made for less than $20 million from a script by writers of NBC’s “The Office,” Gene Stupnitsky and Lee Eisenberg ― a sum that would only have covered Diaz’s salary on “Charlie’s Angels: Full Throttle,” according to Forbes magazine. The actress took a drastic pay cut to get “Bad Teacher” greenlighted. The supporting cast includes Jason Segel of “Forgetting Sarah Marshall” as a gym teacher more suited to Diaz’s character than the rich guys she’s chasing; Lucy Punch of “Hot Fuzz” as Elizabeth’s goodie-goodie nemesis; and Phyllis Smith of “The Office” as a complaisant friend in awe of Elizabeth’s reckless bravado.

“Characters like Elizabeth are mainly written for men,” Segel said. “We’re reaching a time where women are finally getting their due as great comedians. There’s something really nice as an actor about being able to be so nasty with no consequences. Any joke Cameron thought of, she was able to say and not worry about being likable.”

Diaz isn’t always playing the cheerful girl ― in “In Her Shoes,” she was an aging partier freeloading off her grandmother, and in “My Sister’s Keeper,” a mother so unsympathetic one of her daughters sued for emancipation.

Throughout her career, Diaz has both accentuated and shrouded her beauty ― enthusiastically shaking her backside in a pair of Spider-Man underpants in “Charlie’s Angels” and disguising herself in a ratty wig and shapeless outfits in “Being John Malkovich.”

In “Bad Teacher,” Diaz wields her lean, 5-foot-9 body like a weapon. Commandeering the school car wash in a pair of Daisy Dukes and towering over her 12-year-old students in 4-inch stilettos and skintight pencil skirts, she is both the embodiment of the sexy teacher fantasy and a parody of it.

“Cameron knows the power of being a hot woman,” Kasdan said. “She gets all of those jokes. She’s like an athlete. She’s got this enormous control of her physicality.”

In what may be the year’s most awkward sex scene, Diaz and Timberlake share a fully clothed tryst in a hotel room. “The faces he made are so brave,” Diaz said of Timberlake. “What guy would ever make those faces? The noises. He was like, ‘I’m creeping myself out.’ I was like, ‘I don’t even know if I want to know what’s going on back there.’”

That Timberlake and Diaz are exes in real life, the actress said, only eased the shooting process. “That would have been kind of weird to do with someone I didn’t know and trust,” she said. “With somebody else I may not have known where it stood, but we know where it stands.”

Diaz is now shooting her next film, “Gambit,” in which she dons another pair of short-shorts, this time as an ebullient cowgirl opposite Colin Firth. After her stint as the misanthropic Elizabeth, her role in the Joel and Ethan Coen-scripted “Gambit” will be a return to her sunnier persona, Diaz said. “She’s super-engaging and outgoing and wide-eyed. Everything’s an adventure.”

After “Gambit,” Diaz will star in “What to Expect When You’re Expecting,” a comedic adaptation of the pregnancy bible told in intertwining vignettes, a la “Love Actually” and “Valentine’s Day.”

But now that Diaz has played sour, she said she won’t settle for saccharine.

“When I see romantic comedies where at the end you tie it up with the happily ever after, it makes my skin crawl because I feel like you never come to a happy ending in life,” Diaz said. “It’s always just the next progression. That’s what I liked about Elizabeth. I liked the fact that this was only one stop at the station. She didn’t make it all the way. Her growth was this increment. She got that one little inch.”

By Rebecca Keegan

(Los Angeles Times)

(McClatchy-Tribune Information Services)