I also don't understand the problem of people sitting inside, using the bathrooms etc etc even if they aren't watching a show..
Everyone is a potential customer. So we treat everyone who comes through the door as if they were one. The toilets have to be cleaned each night anyway so what does it matter? We are lucky in our area in that the teens are pretty well behaved, but if they do misbehave, we just tell them its not acceptable and if they aren't seeing a film to please move on. if they are seeing a film, we just ask them to settle down. Teenagers are people too.. they can be some of your best customers. They spend the most money on concessions and see the most films. if you set down your tolerances right away, they respect it. Theres always going to be the odd kid or bunch who won't settle, so you chuck them out if theyre bothering others.