Jesus christ... and I thought my old roommates were bad...
-One of my old roommates adopted two ferrets without our permission. They were just there one day. Mind you we already had four cats when we were supposed to have only one. Roommate did not take care of the ferrets at all. Their room was disgusting (they were a couple, we were a couple) and they didn't clean up the room ever so it was always covered in books and clothes. Eventually the smell got so bad that we had to tell them that the door to their bedroom had to be shut at all times. Well, they let their ferrets run around their already disgusting room and the ferrets would poop in the one spot in front of their door that wasn't covered in books/clothes. They never cleaned it up until we moved out.
One day a friend with her friend came over and asked to see the ferrets and this is when I learned they had been neglecting the ferrets. I never saw them so I didn't know. One ferret had dried poop stuck to its butt. The other ferret had its collar on so tight that the collar was actually stuck to its skin and the ferret was barely moving. My friend had to use soap and water and very carefully with scissors cut the collar off. It came off in pieces that broke off. It was horrifying. Immediately after the collar was removed, the ferret gained SO much energy. My roommate just sat in silence the whole time.
After that, I told her that the ferrets had to be moved out of the house and if it wasn't done in a week or two, then I would call a ferret rescue or the ASPCA or SOMEONE to take the ferrets away. They moved the ferrets out shortly after.
When we were moving out, we had to clean out the apartment of course. It was disgusting. They did at least clean up their room and partly cleaned up the kitchen, but roommate was complaining she was tired and had work the next day and went home at midnight - I had work the next day too! We ended up cleaning up - THEIR MESS - until 4am. I say their mess because they used the kitchen way, way more than we did and would make huge meals in it (because they had gaming and people over on Sundays) and would hardly clean up. The fridge was so gross because they let stuff spill in it and never cleaned it up.
Not only that, but they knew for months that we were all moving out and did not plan for it at all. We rented a U-Haul and had already been moving boxes out two weeks prior. They had NOTHING. They never moved out anything and they had much more stuff than us. So when our other roommate (5 people in a 2 bedroom...) was moving out his stuff with his friend, they actually had the nerve to have his friend move out their stuff too. It happened the day of, they planned nothing.
I was pretty angry at the time and even though I kept it no secret what they did and told my friends... my friends still remained friends with them for some unknown reason. So I have had to see her multiple times now. It was a number of years ago, so I have moved on and she has definitely improved as a person (cleaning up her current house, taking care of her pets) but it's just something you can't forget.