It's supposed to ensure there are no surprises after closing.

If they are PVC/ABS look for the clean outs -threaded lids that can be removed- and basically pressure wash the inside of the pipes on all runs.If you are handy, remove the toilette and use high pressure water to clean the pipes, you"ll be surprised with what you can accomplish with a garden hose with a pvc end cap and a couple of drilled holes on it.

EDUCATE YOURSELF - yes, it will take time, but will lead to a selection that better meets your expectations & avoids potentially costly surprises!

I shutter a bit at the "none of it could have been predicted" statement. 60K is a big chunk of cash.Yes, there are many items that can come up but as with house flipping and other renos the small signs can be missed.What items caught you by surprise?

Another fun thing we have done is the key box we stick on doors for a house , put something fun in there, a surprise, and give the kid a code.

I think you would be pleasantly surprised if you ran numbers today. 

Sorry, I never had to deal with tenants directly before but when I called the number I had on the contract they were equally surprised that someone had used their home loan application info and they had never applied to rent). 

EDUCATE YOURSELF - yes, it will take time, but will lead to a selection that better meets your expectations & avoids potentially costly surprises!

Not at all surprised you have high humidity; the hydrostatic pressure is forcing moisture through the pours of the block, past the interior cell (even if not fully grouted) and out the pours of the interior face. 

You can learn a lot from those two things surprisingly.