I live in an community where the people are mostly elderly retiree, and I generally feel like short-term rentals would be unwelcome in this neighborhood. 

Those  are appropriate only for widows and the elderly

Unless your dad is very elderly and you are an only child I would pass. 

I have knocked on doors, had conversations with elderly that are interested in selling down the road, but these have been random experiences.

Absentee owners or landlords that are tired or elderly. 

The other side (well maintained) is rented by a 10-year paying elderly tenant that is only paying $500/month.Questions-"Can" you still BRRRR/does it make sense to BRRRR when you can only add value to one side of the duplex?

The estoppel agreement verifies all terms and is signed by the seller, the tenant, and you to prevent the tenant from coming back later and trying to take advantage of your ignorance.I just had an investor purchase a property 4 months ago from a very sick elderly woman.

But for many of the locals, there are human beings who say "sir" and "ma'am" to their elders and hold doors for them, and there is subhuman trash.

Several of my rentals have elderly parents, some listed as occupants, some as a leasee.

We have a Seller who is interested in a Seller Financed deal (as the subject noted).3-unit, elderly married couple live in one of the three units and have since they bought the property in 2005.