I don't really want to invest in a D-class area.Tangentially, what are some of your "it's time to sell this property" red lines when it comes to the changing economic conditions of an area? 

The city is changing the zoning in the area.

A single-family home or small multi-unit property can be a great way to dip your toes in the water.Build a Team: Even if you’re planning to handle most things yourself, having a good real estate agent, property manager (if needed), and a reliable handyman can make life so much easier.Learn the Local Laws: Pensacola is pretty investor-friendly, but it’s always good to know local zoning laws and short-term rental regulations if you’re thinking about Airbnb or VRBO.Run the Numbers: Make sure you’re clear on the property’s cash flow potential.

Would definitely check local zoning / code enforcement laws as well.  

I see a little bit of a red flag in the fact that his students are closing so many deals in Texas right now - in such a tight market...

I just bought a lot which I'm now splitting due to the new SFR zoning.  

If you conclude the leverage is so good that everyone comes out ahead that's fine but if you are only able to originate hard money debt that may be viewed as a red flag by investors who will question your experience and borrowing strength.

The 4-plex may be viable if zoning allows it but building another single family is probably not the move.

Quote from @Sherry McQuage: Make sure to check the zoning to make sure mobile homes are permitted there; check for any hazardous waste designation for the area; will you need to have the parcels surveyed out in order to sell the size you intend? 

I want to give them the benefit of the doubt they are just struggling with staffing but now have seen some red flags that lead me to believe there might also be some type of deceit/fraud and possible financial trouble.