My friends and I went to a production of a bad play called "One Foot In Heaven" to support a few friends that were in it. The acting, even for community theatre, was not bad at all! However, the play was just to long and poorly written. We HAD to have a break from the pain so we left in intermission and snuck back in right before Act 3 began. Our friends in the show were VERY understanding.
That is the only time I have done that. There was another time I almost did it.
About it being disrespectful to the actors to leave during the show, I think sometimes they would rather you leave than stay.
"I've always secretly longed for an actress to get to the top of the cherry picker and projectile vomit all over the guards below."- Wonderwaiter in the "Defy Gravity?" thread.
~~~~~~~~My dream? Sutton Foster as Cassie in A Chorus Line