@Jonathan Morrell
What @Chris Mason said. So many cape cod/salt box owners leave money on the table by not heating the second level. It's a $500 upgrade max.
Most off markets I've been exposed to were conventionally financed, but often subject to repairs per plans and specs. However my background is appraisal contracting mostly with institutional lenders. I seldom compiled reports for private lenders and only a few were cash buyers.
Many distressed homes will not sell on MLS. There could be structural issues beyond deferred maintenance, title issues, sometimes boundary lines are screwy and need some legal legwork - any number of things. Fires, pet hoarders, smokers, meth labs, flooding, parties, vandalism, gangs, shot houses, deceased resident (for months sometimes), code violations... The posters on this forum could fill libraries with the circumstances that will cause a property to be distressed and not salable on the MLS.
Every challenge has a solution. Can you be more specific? Can you describe some properties you're looking at? Are they SFR, MF, Commercial, Land, development/redevelopment? Or are you more focused on capital structure in general?