We solved this by converting a coat closet in the living room which backed up to the kitchen, into kitchen floor space where we put the fridge and then moved the stove to the old fridge spot, then put the new dishwasher in the old stove spot and topped it all off with granite.  

Your thinking is spot on.

Sure, location, cash flow potential etc. but numerically, is there a sweet spot?

I have a soft spot in my heart for the aging and our veterans.  

That puts a buyer in a tough spot.

There are mushrooms growing in spots also (see photos).When looking through the windows I can see where the water is leaking from the refrigerator plumbing and looks like some of the hard wood is starting to buckle and the trim has absorbed some water.

My question are twofold: are there any blind spots I am missing when evaluating this deal?

To someone from most spots in CA this may seem like a great deal, but how does it compare to other 4 plex sales, or to per-unit prices for duplexes or triplexes?  

Pittsburgh is one of our sweet spots and we have some great options for you to choose from.

My cabin is also positioned in a weird spot marketing wise, it would not do well as a short term rental as it's not fancy or equipped for family and not large enough and not the right long distance views to compete with the higher end properties.