This is not always the case, but it's especially, desperately and horribly the case in Bewitched, wherein she plays her part with an excess of breathy stupidity. Her character, in fact, comes off like a sexually precocious 5-year-old who just took two hits of meth to help her come down from huffing a whole tube of glue.
This acting choice is decidedly weird, since the original Bewitched was a TV show that featured an unusual concept for its time: The lead female was smarter and savvier than her husband. Yes: Samantha was always two steps ahead of Darren, and that's part of what made the show interesting. While Lucy Ricardo and Jeannie and Harriet Nelson and the vast majority of TV wives prior to Bewitched always had to defer to their more worldly and wise husbands, Samantha was different. She deferred to her husband not because he was smarter than her, but because she was so much smarter than him, and she didn't want to crush his ego with her god-like powers. That's why the star of that series, Elizabeth Montgomery, held so much charm for men of my generation (i.e. the Lost Greatest Baby Xers): She actually seemed interesting, instead of just pretty and pathetic.
In this movie version, though, Nicole Kidman plays the Samantha part as completely naïve and guileless. She's so stupid, in fact, that she gets conned by an actor. A Hollywood actor. Believe me, if you'd met these people, you'd know why most of them did not choose careers in international arbitrage. And Kidman isn't even conned by a half-way intelligent actor: She's conned by someone played by Will Ferrell. So maybe Kidman had no choice but to play the part with a cloying, breathy, baby voice and innocent wide eyes, but it's still incredibly annoying.
The wretched plot and painful acting are hung upon a fairly clever conceit, though: Ferrell plays Jack Wyatt, an actor whose last movie was so bad it could have starred Will Ferrell. After that cinematic disaster, he decides to take the lead in a remake of the television series Bewitched, only he's going to have the show re-written so that his character (Darren) is the comedic center.
Since virtually every movie this summer is a remake of another movie, TV show or cereal box, the idea of doing a movie about doing a remake seems clever and timely. Unfortunately, after that brainstorm hit the page, writers Nora and Delia Ephron must have completely run out of ideas. Every other moment in this film seems like it was written by a copy of Scriptware 7.0 with the "plot advance" feature turned up to 10, the "motivation" feature turned down to 0, and the "joke" feature set to "inverse."
For example, Jack Wyatt hires Isabel Bigelow (Kidman), a complete unknown (and unknown to him, a witch) to play the part of Samantha in his new version of Bewitched. But he only chooses her because she's a nobody, and he figures she'll be easy to manipulate and won't steal the spotlight from him. Of course, she immediately falls in love with him, and then learns of his nefarious plans and starts hating him. Then, for no good reason, she again decides she loves him, and then he loves her, until he finds out she's a witch, and then they hate each other, because, you know, something has to happen in a movie, or it's just a collection of still images.
With no rhyme or reason behind the vacillation of feelings, all we get is the standard story arc of a romantic comedy without any motivation for the plot to move from one point to the next. Which, really, would be fine in your standard Hollywood comedy, since I don't think we expect the story to be something out of Tolstoy. The problem is that, in advertising the film as a romantic comedy, the audience expects not only by-the-numbers romance, but something resembling jokes. There's really nothing sadder than watching Will Ferrell try all his faces and flopping about while reciting dialogue that's every bit as amusing and true-to-life as Condoleezza Rice's Sept. 11 testimony.
One nice thing about Bewitched is that you can't blame its failure on any one person, since pretty much everyone did a half-assed job. The Ephrons' script has fewer good lines than the big mirror on the table at Mary-Kate Olsen's house; a bunch of good actors are wasted in throw-away cameos, and the leads flounce about with no clue as to how to handle this wretched material. There's a little charm from Michael Caine as Kidman's father, but it's offset by a car-wreck performance by Shirley MacLaine as his love interest. Truly frightening: It's like somebody animated MacLaine's corpse and told it to act like it had partial frontal lobe decomposition.
Ultimately, though, Bewitched escapes the limits of its form, and in its subtle subtext, stands as a testament to the power of western culture. Just kidding. It sucks.