just to clarify my comments...I think perhaps I am inexperienced with the range of venues that folks here are performing at. my comments are mostly about concerts where you purchase tickets to see a specific performer.

for example, I went to a show recently where The Builders and the Butchers were the headliner. There was a total of three bands. my ticket was not very expensive and it was a small hall that prolly held a couple hundred people, all standing only. in that situation I would have been surprised and disappointed to discover that any of the music or vocals was coming from a recording! there were three bands, each consisting of 5 to 7 musicians, and everything was live!

but if I was at an event or location such as a street festival, local bar, wedding reception, etc. I don't think I would really care too much whether the performer used backing tracks or lip-synched or whatever they wanted to improve their performance.