Madonna cant Dance is that a joke?, we all know Janet is a better dancer than Madge but The Queen can dance too, as for Britney i been in all her concert tours since 1999 and the last time was at the Staples Center in LA this year, i enjoi her, i don't care if she makes playback or if her moves are not like in 2001, i love her since day one, she's a lovely, tender and shy girl.
LIP-SYNCHING IN MUSIC.
The New York Times reported, "Artists like Madonna and Janet Jackson set new standards for showmanship, with concerts that included not only elaborate costumes and precision-timed pyrotechnics but also highly athletic dancing.

Luciano Pavarotti at the 2006 winter olympics: the performance was prerecorded weeks earlier, "The orchestra pretended to play for the audience, I pretended to conduct and Luciano pretended to sing. The effect was wonderful.

Was the big deal the only people who worry about that are the haters.