I guess it always depends on what the listener expects (and has paid for!) If I am having a few drinks with friends and we are enjoying each other's company then, as a listener I don't care if it is one guy with backing tracks or the radio playing over the bar's speakers. On the other hand, if I purchased a ticket and will be there to watch & listen to a performance, I'm not really very keen on seeing & hearing someone sing along to prerecorded tracks. Not saying it is bad or wrong...just that I would not pay to see/hear it!