if you are a landlord, protect yourself. they will scare away other tenants, some will attract rodents, they will not let repairpeople in. I recommend getting words in your rental agreement to the extent that the law will allow saying how much a person can bring in initially and how much they can add to it. Especially if they are dumpster divers, pick up things off the street etc. You could have an awful bedbug problem. Any used upholstered furniture or bedding is a problem. I don't know how to solve it but you must screen for this, and it is a mental condition so anti-discrimination laws probably apply. It does them no good to have unlimited space for their problem. There need to be limits set and followed. Certainly monthly inspections. Certainly access for repairs. If there are children, there is a child neglect/abuse situation brewing...it is a very unhealthy condition for children to grow up in.