We took a quick sander to the high points, filled in the holes, then over 2 coats absolutely raked on 20-3.5 gallon buckets of joint compound (mix just a touch of water in it).

Most judges aren't stupid and will easily be able to see that their usage went from 100 gallons a day to 2,600 gallons a day after the eviction and will hold the accountable for the costs. 

One thing this crew did was bring in a backhoe, dig a large hole and put 55 gallon drums of car oil, transmissions and engines into the hole and covered. 

I pay $45 per gallon.

Our current options: 1) a couple that vapes and has a small dog (they say they never vape inside, but that's also what all the vapers I know tell their landlords)2) a couple that has 2 large dogs and a 36 gallon aquarium

How can 100 gallons be enough for that many units?  

Also checkout your local Habitat for Humanity ReStore for material deals on smaller quantities like for backsplash tile, bathroom tile, 1 gallon random paint cans, carpet for 1 or 2 odd bedrooms, and scratch & dent appliances.

I buy the same paint by the 5 gallon bucket and don't plan on changing it so it always looks the same. 

A septic tank holds a set amount of liquid and solids , say 1500 gallons . 10 gallons of waste enters and settles , and it displaces the same amount which go into the drain fields .

The problem is the plumbing system, they both have their own 500 gallon (or less) cesspools according to the inspection.