From what I've heard, the process for the dishwashing job interview is very easy. They don't make it hard for you since it's hard for them to find a dishwasher. I honestly don't know why would it be, as many business out there have a dishwashing person available at all times. My best guess is that they want a person out there who's both interested in dishwashing and passionate about movies. So I recommend that if you want the job show both an interest in movies and their movie theatre.
The interview was easy. The manager sits with you, he offers you something to drink and asks you if you want anything. He asks you about where you're from, where do you work or what are your previous works, experience in the field (dishwashing in this case), why do you want to work in the movie theatre, and if you like the movies they play. For them it is important that you show passion for movies, as they have work limitations (such as small kitchen) that they believe that if things get hard your passion for movies and for the experience they are selling is what's going to keep you going.