So far I have used Census.Gov to gather general info on income, demographics, education etc. about potential areas, but the information here is too broad and doesn't narrow in deep enough to assess areas that are more speculative or transitional.

To determine the Zestimate, Zillow uses data from public records, feeds from multiple listing services and brokerages as well as artificial intelligence, including advanced technologies such as computer vision and a deep-learning neural network to incorporate data from photographs.

As I plan to leave the military I have really started diving deep into real estate.

its been that way for decades in many parts of the mid west deep south rust belt areas.. ..  

Go DEEP on that.

Lastly, depending on the Airbnb customer, they will feel either entitled to leave the house a mess or won’t book if you charge what it COSTS you to deep clean the unit (maybe $100-200 per time?).

My wife explained that after we had moved all of our personal belongings, we would need to deep clean her unit, leaving it in the same condition she had received it in.

Doesn't seem to be an over-supplied market, but I haven't done a deep dive on that yet. 

One thing to start working on before diving too deep is to talk to a few mortgage brokers and loan officers to see what kind of programs you can use.

To fill a 500 square foot room with 3 feet of water (which is waist deep) would be over 11,000 gallons.