All I can figure, is that they pay a reputation scrubbing service.My daughter ended up firing them and they tried to tell her she owed them a termination fee and she said, well we can either let that go and call it square, or I can sue you for all of the overcharging.  

Some will not raise the rents of good tenants preferring to supplement their rent in the belief keeping them is preferred over charging full market rent with the risk they will move.

Hidden fees and overcharged rehab costs.2) What checks and balances should I have in place to prevent unscrupulous managers from taking advantage of me (I am located in Southern California and I have a full-time job as an investment banker).

They also claim that we're overcharging them for "small damages".

If you overcharge you are liable to attract very weak tenants who are willing to sign on for any price because they know they can't or won't pay anyway.

Ever accidentally overcharged a credit card, forgot to pay a bill, or misjudged an expense?

And beware of letting them find their own maintenance and repair people they may overcharge you for. 

My first thought was that your PM is overcharging you for maintenance (which is where most PMCs make their real money, in my opinion).

So, there is no percentage of life left in it that you can charge the tenant for.I don't think you'd win in court over charging them for the A/C unit. 

It helps you gauge whether the tradesmen you hire are doing a good job or missing details or overcharging or goofing off.