In the desire to stick to what we want (#1) and get emotional (#3), we might find ourselves with an undesirable deal.

Is probability-adjusted cost of an increase in undesirable occupants really high enough to warrant giving up $2M in valuation on a house? 

All of these point of the neighborhood having high demand and a lack of inventory, usually because the neighborhood is in transition from undesirable to up and coming. 

One of them was run by a local investor and almost fully occupied when I took over, but after I cleared out the non-payers and general undesirables, I ended up turning over 50 of 76 units, which costs $4-5K per unit.  

If you see something undesirable, but not a deal breaker, then you will be better prepared to handle it once the acquisition is complete.4.

It gives me more confidence to be a bit more aggressive and clear out undesirable inherited tenants.

There is no need to go to undesirable areas to get cashflow.

You can only sell D/C- properties to other D/C- investors.thank you Charles, are C areas considered undesirable, high crime areas ?  

It may be possible, but you'll most likely find homes in undesirable areas that are difficult to rent (ie extremely windy areas north of town). 

After years of dealing with undesirable tenants for so long, and because of the outrageous increase in property tax here in Texas, they are now considering selling to ease into retirement.