I only had one problem finding a seat at a theater. I decided to try to go to a premier with someone, and it's odd that when you have two people looking for a seat in a crowded theater, there are only scattered singles. When you have three, there are plentiful doubles, but no trips. Annoying.
As for bad movie theater behavior, there was only one time that the theater had to pull out the big guns. It was a "horror" movie from 2005 or 2006 about a babysitter and the killer was 'ZOMG, GET OUT OF THE HOUSE, HE'S CALLING FROM INSIDE!' I don't remember the name of it, but a rather large percentage of people who bought tickets to this particular showing were teenagers, and so they had several staff members in the theater shooshing anyone who caused a disruption and ready to eject them from the theater. Good move on their part. They even told us at the window that a bunch of kids bought tickets to the movie, and that they would refund us our money if it got too out of hand.