“I think he’s one of the greatest artists that we have today — but he could also be the worst,” a collector says in Maurizio Cattelan : Be Right Back.  For more than 20 years Cattelan has garnered praise and scorn for his works, like a sculpture of Pope John Paul II struck by a meteorite; a functioning 18-karat-gold toilet; and a statue of a praying Adolf Hitler. But who is really this guy ?