I'm not fond of lip syncing most of the times. But I'm not necessarily offended when a performer does lip sync. If the performance is very physically demanding (or other factors are inhibiting their ability to sing i.e. weather) and the performance itself is good, I usually (as a viewer) let it slide. I only really hate lip syncing when the performer isn't doing anything to hide the fact that they're lip syncing to studio versions of their songs AND are giving mediocre choreography/performance. If it's clear as day that they aren't giving it their all in the performance, lip syncing only makes their performance look worse than it already is.
