These days, I generally only go to the movie theater if it's something that's going to be SERIOUSLY improved by seeing in theaters and being fully engaged. Pacific Rim, Inception, Whiplash? Absolutely. No regrets whatsoever. A comedy, period piece drama, documentary or standard action flick? I can wait until it's on Netflix or rent it for $1-3 in a few months.
Also, yeah, management isn't wild about people sneaking in snacks. According to the manager I had when I worked at a theater during the summers, the ticket sales are just enough to keep the lights on, generally. Concession is where they make actual profit. I don't have any real issue with sneaking in food, and chances are the low-level ushers there don't either. That said, pleeease do them the courtesy of being properly sneaky with your food. They don't want to have to alert their managers or tell you 'no' any more than you. Sneak it in, eat it quietly, and properly dispose of it - leaving a mess of clearly outside food is especially rude.