She then proceeded to harass the landlord and property manager about EVERYTHING- the sewer, the gate, the garage - everything was not to her liking.

I understand that even modern multi-families may have main disconnects that are fused.  

Added a detached garage.

Haven't seen your posts for a while.I grew up in a mixed-use property where my dad had his store, and there's a small apartment behind the 2 stores, an 8 room apartment upstairs, plus 4 garages.

David OrrTax Modern

Or a SFH that has a detached garage or work shed and convert it (running electrical and sewage might be expensive so do your due diligence).

She also found that ALL the entry doors to the property were unlocked, the AC was on (set to 71 degrees), and the lights were on in the garage and a couple of rooms.

I was quoted $800 by a property manager years ago to replace a $150 garage door opener.  

Can anyone here send me a sample estimate for Garage Conversion?

Some of our rents are a touch low yes, but a good number of them are above the area average... it's hard to put all of this into a single post because we have everything from small 1 bedroom efficiency apartments to large 3 bedroom/2 bath homes with additions, big yards and multiple space garage areas.