On one hand I think being that the unit is next to and above heated ones it will be OK, especially if the danger zone for pipes is 20 degrees and the temperatures look like they’ll be in the 30s for the week with only a few dips.

Was the government truthful about the efficacy of the Covid 19 vaccine and it's dangers?

The home in certain area would rise if there're few recent home buyers that overbid the market, with just 3 comps the entire neighborhood could rise a lot, but that also pose a danger to the market because when interest rate is rising, the demand is slowly reduced.

Asbestos inside the home, ie insulation, is dangerous to remove yourself.

If the animal is higher risk (cats, animals owned less than one year, dangerous breeds) then I charge additional fee up front before the animal ever moves into the property.

Property managers may be good sources of info for what neighborhoods are generally good and those which are dangerous.

There has been an explosion of real estate Gurus.

That said, I believe any training classes give you enough information to make you dangerous.  

Once you adopt the premise that there is no rent advantage to a nicer / bigger B class property... the most lucrative place to put your money is where you will spend the least amount for the property, down to the point that the other negative "D class factors" override that formula (dangerous neighborhoods, drugs, and the other "looks like / smells like crap" comments the original poster mentioned.  

The one caution I would give is that there are some very good areas and some incredibly dangerous areas in which to invest.