And in most cases, reading a receipt and knowing which property/my management company it is tied to (done automatically by separate accounts linking to my software), even if I don't do a very good job documenting, I have enough to go back and justify almost any expense.  

His documents are comprehensive & they make up the majority of the ones I use in my business.

Photos of how good the place looks, with a lot of close up and far out photos, not just of the documented issues.  

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

Since most properties on the market here have inspections and a disclosure packet up front, it will be difficult to get those documents without MLS access. 

So creating all these funky financials is great, but if you are using those in a presentation that information should be in the PPM or an official document as if someone is making a decision based on that - it can come back to bite them.

If the police came they probably did not come and document the damages, get the report.   

Quote from @Lolo Druff: Just like turn signals, you should always trust, but verify that the seller is telling the truth.Your offer to purchase should include a requirement that the Seller provide all documentation and agree to sign an estoppel certificate (also called an estoppel form or agreement).

Proper documentation and consistent reporting are crucial to ensure compliance with IRS requirements.

Document all of what you do if you are going to get it done for them, and/or if you cut them a check then make sure it is in writing that it was all done and they cannot come back to you at a later date asking for more money/mitigation.