Sure, music stars are under enormous pressure to deliver perfect "live" vocals to thousands, millions and even billions of viewers.
But when you're being paid squillions like Britney, Madonna, Mariah, One Direction and Chris Brown, it's hard to excuse a dud mime job. Not quite music to the ears, hey?
Singers employ all kinds of strategies to convince us they're singing live: the ol' "earpiece adjustment", "close-eyes-to-hit-high-note" and the painfully insincere "talk-to-crowd" technique, making us feel in safe hands.
Join us for a cringe-fest as we check out the most obvious lip-syncing fails in our latest video slideshow: