If i wanted to convince them to move because they were an undesired tenant, I simply raised their rent to above market rent. 

Even cash-flowing properties could be undesirable for a bank’s risk appetite for refinancing.

The seller had strategically purchased the building to remove an undesirable landlord from the neighborhood but had no intentions or interest in repairing it.

See guidance at the CA department of consumer affairs (http://www.dca.ca.gov/publications/legal_guides/lt...).When purchasing a property with inherited tenants, I will aim to keep the existing tenants subject to two things: 1: do they keep their place up appropriately, or are they undesirable to the environment I want (ie: I have decided not to keep a hoarder who kept 4 animals inside the house and had an adult child living in their garage, and a house where one of the tenants was dealing drugs) or b: the unit is in reasonable shape and does not need a full rehab.If I decide to keep a tenant in place, I will generally do work around the property and in their unit before I proceed with a rent increase.  

If something has been sitting on the market for too long, odds are that the price is too high and/or there are some other undesirable features with that unit.Once I find comparable listings, I'll usually put them into a spreadsheet and look for patterns, this lets be go back and look at what other people posted once the listings are removed.

The ability to deal effectively with undesirable residents. 

Is there anything about the location that is undesirable?

If you bought in an undesirable area/neighborhood then this is a bigger problem.

My late charges are designed to discourage undesirable behavior, not really as another income source.

We use cap rate to evaluate a property and to get a 10% cap you usually have to buy extremely distressed properties or buy in undesirable areas.