Reading this thread is strongly influencing wether or not I should return to nursing in a few months or stick to dog walking. So far, dog walking is working.
I once walked in to find an ignorant prick drinking from the large bottled water I bought earlier in the day, straight from the fucking bottle. When I asked him what the hell he thought he was doing, he got very indignant and told me to calm down, he was going to refill it with the rank tap water. He then went of to bitch to the rest if the staff about me being a silly bitch.
I used to buy the odd thing from a health shop near work and put some items in the fridge freezer, until home time. There was loads of room before I get accused of hogging the fridge. I walked into the lunch room to find a cheeky fucker sitting with a spoon, eating MY VEGAN ICECREAM directly from the tub. She just said, "I was really hot and knew you don't mind sharing." 
. She was my senior so I just walked back out. I was on a low wage and this stuff is really fucking expensive.
I used to buy the patients and staff cheap fruit lollies during the summer as it was an old ward and got really hot. I was heading over to get something for later and was told by a staff member, "just buy the orange ones today, I don't like the pineapple". I decided I wouldn't give them so much as the smell of my fart from then on. 
The confused looks when I arrived back, with just enough lollies I counted for the patients was a joy to behold.
The nicer you are the more you get screwed over. I've changed a lot due to the last couple of years, while I've been on unpaid leave, and I think I might well loose it if I went back to that shit now.