TLDR: Bad idea for your personal home.

Neat idea.

And, these were typically also underwritten with the idea that a downturn was inevitable.

That's a good idea too, or a personal guarantee potentially if they signing as an LLC. 

I don't have anyone else in my household other than us so no idea, but I've never been asked the question either.

Again, I like the idea of a new fourplex, it just seems like you’re glossing over alternatives/possible problems. 1) You say you want to hold for cash flow instead of taking $120k cash by selling as soon as it’s built.

I am about to run Facebook ads but I have no idea how far this "scammer" information goes.   

Always willing to get a beer and just bounce ideas and hear what anyone has to say.

I'm ASSUMING (a bad idea, I know) that they were a married couple and had joint ownership. 

There's not a ton of information about this topic so i'm just curious on how investors are running their comps on their small multifamily investments.