1) Strollers. Sorry, Mommie. Sorry, Daddie. Your stroller isn't a weapon, battering ram, or an automatic green light for you to push ahead of anyone. For those of you who use strollers responsibly, bless you.
2) Some parents of kids in strollers. Uhhh, if you've been in the park since 9 am, and it's now 11 or midnight, and your child is either zonked out or crying bloody murder, that's just wrong, and very selfish.
3) Rude people. Wide category. You know the crowd. Will wait until the parade starts and then try to squeeze into the 3 inches in front of you, won't move all the way down the aisle, people who talk during the pre-shows, people who sit on the floor when they've been told 18 times to stand up, people on busses who put a bag down on the sit next to them so no one can sit there, etc.
4) Rude CM's. Doesn't happen often. When it does, it really sticks out, and makes a horrible impression.
and finally,
5) Anyone who walks into the Rose and Crown pub in Epcot, orders several extremely light beers, and leaves a few coins for a tip. No clue.