We have been known to take a bit of grief over the debate of keeping the integrity in live music. Pitch correction heavy effects chains and backing tracks. Today many bands play with backing tracks or sequencers to improve musical depth and performance quality. I have even run sound for a band that was all backing tracks with vocals being the only "live" aspect of the performance. Personally I don't approve but when I am behind the board I have a different set of priorities. Our job is to take whatever we are provided in the way of performers on the stage and make them sound as good as possible PERIOD.
Some of these bands are capable of playing but choose to avoid the inconsistencies around musicians and their many moods, others are the benefactors of production in a studio that goes beyond their talent levels. Once a band is on our stage it is all about sound quality.
When we select bands we will not recommend bands that do not perform live. This is really the only time our opinion matters on the subject. Live sound is meant to be live and talented bands performing live provides a much better show than hyper produced tracks absent any human feel.
This said we still have to be prepared for lip synced performances or the band playing for the first time live. We use pitch correction and any other processing needed to maker a performance the best it can be. We side chain kick to bass compression to tighten sloppy bands and have been known to pipe excessive kick drum into the monitor mix to keep a band together. Our goal is to always provide the crowd with the best experience possible. We do not employ engineers that say things like "That's what it sounded like going into the microphone, I just made it louder".