When theaters allow movies to run with faulty sound or projection because they're too greedy to care, people should get angrier.
Some movies are important works of art, and even the ones that aren't are often at least culturally significant. You can only see a movie for the first time once, and in most cases the first time will be the only time. Movie theaters aren't like any other business. They're not selling you merchandise that can be returned if defective or services that can be offered gratis if unsatisfactory--they're responsible for the entire population's entry into our era's most important art form. So when they dim their projector bulbs to save a few bucks or play movies in theaters with blown speakers or refuse to pay a kid minimum wage to stay in the booth and make sure the screen doesn't go black for an entire scene, they're not just giving you a bad product for your money, they're permanently spoiling your experience of a cultural event. And you should be pissed.