Always make the audience suffer as much as possible.
One of Vladimir de Pachmann's favorite tricks before a recital was to play about with the piano stool, adjusting and readjusting it, until the audience became desperate. Then he would rush into the wings to fetch a large book, place it on the seat, and try that. He would indicate that all was still not satisfactory and would tear one page from the book and try again.
—Little, Brown Book of Anecdotes
In reality art is always for everyone and for no one.