In the pop world, Ashlee Simpson always seemed like an inevitability. Riding the coattails of her infamously dense sister, Jessica, she parlayed her own MTV reality show into a No. 1 debut on the Billboard charts.

But during Tuesday night's Orange Bowl halftime show, a stadium filled with 75,000 rowdy football fans gave Ashlee something that was probably equally inevitable: a thorough booing.

After a performance of "La La" in which she couldn't even sing in tune with her "guide track," Simpson finally got the reception she has deserved for a while.

Outside of television studios controlled by producers and beyond the reach of deejays dictated to by radio programmers are ordinary Americans. And when a highly paid star like Ashlee Simpson chokes, they're not about to give her some courtesy applause.

That's because Simpson has flouted one of the founding principles of showbiz: Never let 'em see you sweat. In being so ill prepared for the national stage, she has become the Wizard without his curtain, the Emperor in his brand-new suit.

Live at the MTV Video Music Awards pre-show in August, Simpson's odd, ear-grating performance left people talking. During her first lip-sync snafu on "Saturday Night Live" in October, she actually had the gall to walk off the stage and blame her bandmates for the miscue. Any performer worth her salt would have turned the sticky situation into a success.

Just think of Melissa Etheridge, who struggled with a faulty microphone and detuned guitar during the sold-out, nationally broadcast Concert for New York at Madison Square Garden in 2001. Where Simpson would have smashed the guitar and stormed out, Etheridge persevered and the audience loved her for it.

"What you want is a final product that's fun," says Sasha Frere-Jones, music critic for The New Yorker. "Everybody uses guide tracks. But being a bad sport, walking off stage and being a bad performer - that's her fault."

As an audience, we enjoy being beguiled. It was true 100 years ago for Houdini-heads, and it's true now, even with the dubious offerings of David Blaine and the debunkings of Penn & Teller. It's such a pleasurable experience that we'll fork over our hard-earned cash for the pleasure of being bedazzled.

But when performers botch the spectacle or reveal how they duped us, we get angry. That's what made rotten produce the bane of 19th-century performers and it's what drove Milli Vanilli into the annals of shame.

Lately, we've been besieged by public shams, from Jason Giambi's alleged steroid use to never-realized assurances about Iraq's weapons of mass destruction. But it's hard to voice our dissatisfaction.

Ashlee made it easy. She took the stage. She sounded bad. We booed.

Yet the Simpson juggernaut charges on. Six months after its release, her debut album, "Autobiography," is still in Billboard's Top 40 and is closing in on the 3 million sales mark. Ashlee, meanwhile, is unfazed by her detractors.

In the upcoming March edition of Teen People, she tells music editor Zena Burns that those who complain about her "are just old people who watch the news and don't know anything about me."

She has a point there, since the teen viewers of MTV's "The Ashlee Simpson Show" got to see and hear her struggle with off-key warbling throughout the recording of her album.

"They see her on the show and she's scrappy and she's a real girl, and that's someone they can relate to," Burns says. "'Here's a real girl who makes real mistakes just like me. But she also makes this kick-ass music.'"

While she might not actually live up to the level of "kick-ass," Simpson does sound competent on record. But until she figures out how to take a stage with a modicum of grace, all we can ask is that she stop exposing us to her wailing - and herself to our ridicule.