But for the purposes of this explanation let's say you're my client and this is your first deal with me. 

great explanation ^

His primary mortgage was sold to a private lender in the early 2000s and he claims he had to give an explanation each time as to why he financed with a private lender with such poor reputation every time his credit was pulled.

You failed to include what I wrote earlier:  All of this can be found online in some shape or form & if someone wanted a deeper explanation, contracts, etc. they can obtain this information/material for significantly less through a CPA, attorney, etc.

Here's a fundamental explanation to get your juices flowing:Assume a house costs $200,000 and rents for $1,500.

Security deposit amountYou can find plenty of examples by searching for "tenant estoppel certificate doc" or exchanging "doc" with "pdf" for more options.Here is an example and explanation: Sample EstoppelSome have a lot of legal jargon but this document does not need to be so detailed.

Even though I live in Charlotte, I've spent a lot of time doing loan mods and short sales in places like New York, New Jersey, Philadelphia, Nevada, Arizona, Washington, California, and Illinois, and have seen the possible trap of only being in one area.I've seen landlords who were intensely renting in a certain geographical area get decimated due to the changes in the marketplace in their locality.

You also haven't shared what attempts you've made to reach out to them for an explanation... 

I have investments that send on-time quarterly reports with documents like rent rolls, expense reports, detailed explanations of whether we are in line with initial projections or not and if things have been improving or not and why.

Also to buy the majority of those in a new state where I haven't invested before, to diversify my portfolio geographically.