You may find the best deals are the really ugly properties, especially if they are in such bad condition they cannot get a conforming mortgage. 

@Benjamin Dutil Most conforming loans and portfolio loans are going to require 60 days of statements (so you need 60 days of seasoning in the account to get past this).

It really does depend on the property type (condo, single family, 2-4unit, etc) and loan amount (Fannie/Freddie conforming loan limits or above), but as @John Leavelle stated it can be 70 to 80%. 

They keep their loans in house so they don't have to follow all of the conforming mortgage guidelines.Nice problem to have, BTW!

Previous poster is correct--if you want a 30y fixed rate conforming mortgage, most lenders require 25% down on first 4 investment properties (then 30%).  

Most conforming lenders will use the rents included on the rent schedule, depreciate them by 25% and use them to qualify you.If you tried to refinance after the purchase and did not yet have renters in there, at that point most conforming lenders would not give you rent credit until you have a lease in place.

@Jae Ham  Many properties have approval for a "Non conforming" use.

While the industry does have many commonly used acronyms and terms the utility of those lacks conformity.  

These lenders make all kinds of claims... is it ok to ask for an example/typical TRID-conforming Loan Estimate in order to see all the details of a particular loan product?

If $595k is above the conforming and (if applicable) conforming high balance loan limit in the area, then it's a jumbo loan (it's $636,150 for SFRs in the most expensive areas, like the Bay Area and Los Angeles), not a Fannie/Freddie loan.