The best ones I had were in grad school. We finished our classes around 4, so we would all pitch in and do dinner together to save money (they were open to eating actual vegetables and meat cooked from raw, bless) and most days go to the gym, and then we'd go in our rooms for the rest of the night and leave each other alone because we were all drained from socializing. And they were super clean. It was great.
The worst I had were also in grad school. They deep fried just about everything, so there was constantly grease splattered on the wall, the stove, the cabinets, anything that would be left out on top of the cabinets... The nastiest part was, though, that they'd use the same grease over and over. I'm talking for months. So we just had this pot of old grease sitting uncovered on the stove, full of chicken fat and bits of breading. Well, I say that was the worst, but I also saw where they'd thaw out raw meat, decide they didn't want it, put it back in the fridge, bring it out the next day but nope, back in the fridge, repeat. They also left dirty dishes in the sink for weeks at a time. I asked them once, knowing that they played board games probably four days out of the week, if they couldn't spend just a few minutes of their Yahtzee time loading up the dishwasher. They said no. I had to pay 200 to break my lease and move out to another unit.
Most of my roommates have been "weird", I guess, but that's always worked out. There were a few that used to grow algae under the sink in undergrad, and the aforementioned "best" roommates and I used to find things around the house to look at under the microscope.
I live on my own now and it's so much better.