Almost anybody who has lived with other people has a story of a roommate who was horrible to live with, some of which are a lot more hair-raising than others. The fact is, everybody has different ideas of what is an acceptable standard of living, and some people are always going to see those they live with as resources to use as opposed to equals that they share a home with.
There is even more potential for things to be tense and high-stakes if one of the roommates is also the individual to whom everybody else pays rent. On either end, it is easy for the privileges of this arrangement to be misused, with upsetting consequences. It is important for everybody to be careful who they share their home with, but that is especially true when the matter of money is so intimately involved with whatever arrangement is going on.