We've had a couple of disinterested audiences in the past, at a couple of function things where we were just the hired background music. Best thing to do -- the only thing to do -- is shrug your shoulders and treat it as a paid rehearsal (and in the case of a Brighton gig we had, a free weekend away). Anything except slag off your audience, because no matter how good a band you are, a toy-throwing will end up going viral on social meeja, you'll look like a prize knob, and your hard-won reputation is in the toilet. Suddenly you're no longer "this really good tight band, you need to see them", you're "meh, don't bother, bunch of primadonnas".
I can pretty much guarantee that the first thing Wayne Kerr's manager said was "what the fck did you think you were doing?? Have you lost your mind??"