Of course Britney isn't going to admit to lip-syncing when she is trying to sell out shows to the GP! Britney admitted to lip-syncing in her interview with Diane Sawyer back in '03 when she wasn't obligated to doing such shows.
People seriously think she's that stupid that she doesn't know her mic is off? Why do people make her look like such an idiot? She knows the mic is off/low. When you're a singer you have to be able to hear yourself.
I wouldn't rule it out this is team Britney after all.
OMG