Let me just put this out there: nobody goes to a Britney Spears concert to be wowed by vocal acrobatics. She's no Celine Dion, people, but that's NOT why we go see her!
Britney shows are chock-full of awesome choreography, great dancing, incredible production, and, of course, hit after hit after hit you can sing along to. So when I heard that Britney may have been 'caught lip-syncing' during "Perfume" at her Vegas show... well, I'm not mad!
People say you can hear Sia's vocals instead of Brit's (Sia co-wrote the song) and that Britney may have used the track to guide her vocals, which was then accidentally fed to the venue speakers.