Flash photography where it isn't allowed, as it not only interferes with others' experiences of the ride/show, but it can physically harm me to have a bright flash of light in a dark ride/room due to one of my disabilities. The light itself is painful and it could also trigger my condition, which could make me very ill for the rest of the day or longer. There are plenty of places at Disney where flash photography is allowed, so just take your photos there, please!
Parents who drag their sick (with colds/flus/etc.) kids around Disney all day and night. Not only are you infecting others, especially if you haven't taught your kid to cover their mouth with their elbow or shoulder when sneezing or coughing, but your poor kid needs their rest instead of being out from park opening to EMH ending! I was once sick for just over one month (yes, month) thanks to this situation of a stroller-aged kid hacking into the air (no covering his mouth or wearing a mask) at a nearby table at Le Cellier for lunch - and a day or two later saw the parents still dragging the sick kid around during Evening EMH. I felt bad for the kid!
Rude CMs. They're few and far between, but when they are rude, they tend to be very rude. If someone asks you a simple question, such as confirming that they are in line for the correct bus at the end of the night, there's zero need to snap at them!
Rude visitors. I am disabled and was sitting in the disabled seating, my service dog quite visibly laying at my feet, on a bus that had only my friend and I on it. We stopped at another bus stop and the driver started getting things ready to bring the waiting man in a
scooter onboard, in the second disabled seating section which I was not sitting in. All of a sudden, the scootering man's wife came on the bus and started literally screaming at me that I had to get up from my seat for her husband! Seriously, what the?! Thankfully, the awesome bus driver put her in her place and told her that under no circumstances was she to ever yell at his passengers! She calmed down enough to have a friendly conversation during the bus ride, though you could tell she was embarrassed at her actions.
On a bus with no more seats available, but room to stand, able-bodied people who refuse to get up from the seats marked as Disabled Priority seats for people who need them due to disability. If you choose to sit there, you choose to be in a situation where you might get bumped from your seat so someone who cannot stand/balance while the bus is moving won't start playing Human Dominos in the middle of the bus ride. Same thing in the accessible monorail vehicle.
Disney's buses that force crowds of people to stand. I just don't think it is very safe and wish they could design a bus like a ride vehicle/the MK train with seats all the way across (the bus could either be open-air or the whole side could lift open) and dedicated wheelchair/scooter area in the front (like on the train).
Me for not having gone to Disney in I think it has been three years!!!! Wahhhhhhh!