“Who’s Mr. Blackwell?” demanded Beyonce Knowles of Destiny’s Child, who learned while walking the red carpet at Wednesday’s American Music Awards that she’d recently earned a worst-dressed jab from the fashion pundit.

Glancing down at the Pocahontas-esque suede minidress that her mother, Tina, designed, Knowles delivered a message to Blackwell.

“Tell him ‘thank you.”‘

Not everyone at the 29th Annual American Music Awards displayed such sartorial bravado. Most women opted for basic black. From LeAnn Rimes’s ladylike satin to Alicia Keys’s veiled hat, the looks at the Shrine Auditorium were stylish, yet staid — rock ‘n’ roll’s equivalent to the dreaded “dressy business.”

Even trouser-loving Nelly Furtado went for the little black dress.

“I’m really not that picky,” insisted a covered-up Mandy Moore, whose ankle-length black dress and Hepburn updo were a shade too demure for any pop star.

After all, what’s a music awards show without a little sparkle and skin? At least Britney Spears didn’t disappoint, wearing a shocking Pepto-pink Versace (though it was still tame by J.Lo standards).

But the evening’s tacky title went to Pamela Anderson, who shrugged off comments on her skimpy chain-mail choice.

“I don’t think people are looking to me for fashion advice,” said Anderson. “Maybe on what not to wear.”