It's easy to become disheartened when dealing with issues such as these. Most landlords do pride themselves on being decent folks who maintain their properties. However, if you have to get someone out who, for example, has not paid rent be prepared to be called everything, include slum landlord (probably the nicest description they will toss at you).
I'm on a couple of tenant forums on facebook and it's pretty eye opening on what some tenants assume they are owed, including the ability not to pay rent because, after all, the landlord is rich, greedy and generally scummy and free rent should be a right for all tenants.
I find that when it has reached this stage I just follow the legal steps in my state to get the renter out of my property. No discussion, no begging, no pleading, etc.. Often attempts to settle these issues on what one might consider a realistic basis often only shows you are dealing with an unrealistic person. Letting the law (whether this is hiring an eviction attorney or simply dealing with the steps to an eviction in your state) handle this helps to take you out of the loop as much as possible.