I guess the biggest pet peeve of mine at Disney is rude people who, wholeheartedly, believe that they are the only people who matters and are entitled to everything.
This encompasses people who:
-take flash photos in dark rides
-instead of going to the end of the row, stop in the middle
-push and shove to see a parade that they didn't wait for
-believe that they can smoke anywhere they want
-purposely line jump even though they don't have any family ahead
-rudely push through to get into a show like it was the last show EVER
-think that Disney characters are there for them alone and allow their children to encroach on others' time with the characters, especially at character dining
-think that they are the only people in the world who deserves to enjoy Disney
Some of these things do happen by accident and most are very apologetic. For instance, on one of our rides through Pirates, someone behind us took a photo and was immediately horrified when the flash went off. They apologized to everyone immediately and never took another photo. When we docked, they apologized again and everyone was fine and even joked about it. Also, I've seen so many people who sit down in the middle and as soon as they heard the announcement again, they jump up and move to the end of the row. Now this is fine to me. However, when they sit there and stare at you like you did something wrong by waiting for them to move. Now that's rude and all they care about is themselves. Apparently, THEY deserve to sit in the middle, no one else.
On the other hand, I did want to say that we have met many very nice and polite people at Disney also.
Sorry that went too long.