I have a friend from way back who works at a local law firm that handles all of my debt collections, evictions, etc.
We have a great arrangement where they're paid on a 'bulk basis.'
The pain in the ass is the apartments. Without giving out proprietary info, I have few competitors renting out as new or as nice apartments for what I can, and still make a nice margin - but the apartment business is replete with turnover. So it helps to have the eviction process on autopilot with a law firm that does a great job and charges reasonable fees (one paralegal and one legal secretary there do most of our work - my friend only gets involved when someone contests an eviction and a court appearance is required).
The commercial and office market isn't nearly as much of a headache, when times are good. Office is a real headache now, not because of having to deal with turnover, but because it's dead.