There is one well known inspector that does not pass a unit on the first inspection.

GC:  this you must pass a test take continuing ed and be licensed bonded and insured.What happens up here IN PDX is the flipper follow their competition and when they see mom and pops competing against them they file complaints... especially the foreclosure buyers.. and then you have the HML who will turn in any private investgor they see funding deals.. as its required to be NMLS licensed to do loans on any 1 to 4 unit regardless of purpose or if its to an LLC or what have you..

As for the applicant's current landlord, you have to take what they tell you with a grain of salt because they could just be trying to pass a bad tenant off to the next guy. 

I even had to pass a background/credit check just to get on the waiting list for one.  

My advisor (CPA and experienced landlord) included a clause in the Holding Fee Agreement that it would be refunded if the tenants failed to pass a screening or credit check.

I actually had to pass a background and credit check just to get on a waiting list for one of these places, and pay the application fee.  

Adjusting the payment standards happens on an at least yearly basis, and if market rents go down or the government no longer chooses to fund the program/chooses not to pass a budget, then yes, obviously rents can go down, but the first risk is universal no matter who you rent to, and the others are seriously problematic even if you don't have anyone on a voucher, provided funding is cut, reduced, not passed, for something related to your tenants.

@Steve Rozenberg right now the tenant pool is so strong that new tenants need to show they can pay the rent (job or plenty of cash), excellent credit score, pass a tenant screening w/o problems and be able to pay all the deposits etc. 

And it looks like it's completely legal to simply offer month-to-month agreements across the board.Next, they'll pass a law saying you have to have one-year contracts for all of your tenants. 

Sure, I'll be able to pass a fortune on to them when I die, but they will resent me for not being there when they needed me the most.