These sellers either are not sophisticated enough to require proof of funds, or have properties difficult to sell conventionally and are willing to forgo POF in hopes of making a deal.

Any tips at all on how to do anything more sophisticated for my due diligence aside from flip through Google, look to see how BBB lookup goes and hope for the best.

But not to a casino.

A lot of sophisticated buyers who are interested in safety deem those markets to be safer, and as such more valuable. 

My city, Richmond VA just announced a large $350 million casino development with hotel restaurant spa etc.

BUT... you need to be somewhat sophisticated and be able to use formulas like IRR, PV, Lookup Tables, etc.

A casino doesn't gamble, the individual player is gambling but the House isn't gambling. 

@Jock Tilghman I don't consider myself a very sophisticated investor but here's how I've been doing it: I simply wouldn't purchase a property if I wasn't very confident that it would rent for at least a $3-500 more than the monthly payment on a 30 year fixed mortgage.

There is some sophisticated planning that can be done to maximize the step up and accomplish your goals.

. :)  like I said for the nicer more sophisticated renter I get that for sure. !