I think it mostly about cleaning...
I lived with my best friend (girl) for 3 years and yes we had some fights, but we could look back and just talk about it, and now when we think about it we agree that it was childish and we are glad that we could talk and get over it, some other roomate cannot. It is important to talk with your roomate when something is wrong, because if you don't tell them they don't know what you think!
We had a great time togheter, we had to split because we wanted to move out but we both wanted something different (she wanted a dog, a house, far from the University, no rugs... I wanted a place where I would pay less, not too far from the university...)
So now I am living with my other best friend (guy), its been a month now and we love it :)
We have to forget about the 100% perfeect relationship with our roomate. It wont happen. We will have some fights, but it is important to talk about it and change something if needed, and to listen to each other.