George, to rephrase your question, how many performing musicians would be unhappy if an exit poll of their audience revealed that they were all completely indifferent to what he/she had been doing? Your guess translates directly to the performer not caring whether his performance touched any of his audience at all. And I say you're wrong - my guess is, all of them would care.
"Entertainment" doesn't mean the old-school "vaudeville/music-hall entertainer" of the Les Dawson school. A quick check online shows a good definition of "entertainment" from WordNet: "an activity that is diverting and that holds the attention". So by definition, if the performer has held their attention with the quality of performance, that means the performer has entertained them. They don't have to be doing a tap-dance and juggling...
And if anyone is getting up on stage *without* the intention of keeping the audience absorbed in their performance, please let
us know who they are so that we won't waste money on tickets to those shows!
Matt, re your comment about Bert Jansch, my dad was one of those disgruntled audience members at Bristol Uni back in the early 70s. By his report, Jansch turned up pissed, drank some more, and the "performance" consisted of quarter of an hour of drunken strumming and incoherent bawling before stumbling off stage. Anyone who *didn't* feel cheated after that needs their head examining! ;-) They certainly did - the whole crowd demanded their money back, and got it too! There's a big difference between "not providing what they were expecting" by playing a different style of music but still playing skillfully, and "not providing what they were expecting" by simply being crap and unprofessional. As Jansch's biography makes clear, he stopped touring because alcohol addiction made it impossible for him to perform even semi-competently and no-one would hire him any more.