I made a habit of running three lenders for the same loan to see who would give me the best rate and/or cheapest closing costs.

@Troy Seals figure out a good system that works for you and get in the habit of documenting as much as you can.

The market has a way of keeping itself level, when the market goes down like this it has a habit of overcompensating before leveling out again to normal, in which if you buy a property now and sell it during that overcompensation period, you can get the most “ bang for your buck “

At the same time, the first tenant (let's call them tenant A) feels like they are in harms way. 

Although the idea of ten thugs sounds like fair justice, it could also be seen as assault (threat of harm).

Books on biz and real estate that I have really like:The Book on Managing Rental Properties - BiggerPocketsABCs of Real Estate InvestingStart With Why - Simon SinekTax Free Wealth - Tom WheelrightThe E-Myth - Michael GerberCurrently reading: Extreme Ownership - Jocko WillinkOn Deck: Gary Keller's The One ThingThe 7 Habits of Highly Effective People - CoveyDon't recommend: The Oz Principle.

I like to view their spending habits as that is an indication of monthly debt they pay. 

If those cannot be rented out because of the condition, you may have to cover the costs out of pocket until the units are in a habitable condition.

@Tony Szymczak the Zestimate isn't worth much, when just starting there isn't a quick way to filter, once you get in the habit of analyzing things for a few weeks you'll be able to tell by looking at house if it is worth analyzing or if it isn't worth your time because it is so far off.

The neighbor across the street detailed how it went from habitable to uninhabitable.