Avoid the national players.

You and your husband were very smart to ask Open Spaces good questions and not ignore the red flags that surfaced through the process. 

One thing that hasn't been mentioned so far here are the psychological red flags and possible pitfalls involved in the process of moving out of and then turning your old home into a rental property.

You probably won't get caught are famous last words for many people with red cards on their properties before listing it, closing it to flip and sell, or to turn into rentals.

Start sourcing deals and become a deal magnet.That's one option.....I'm sure there are many.Find out who the big players in your town are. 

In fact, the only time we ever had an animal do more damage than the deposit was on a set of tenants that had red flags but we accepted them anyway against our better judgement.

His approach could be working when supply and demand is having 1:4 ratio and they're super host with good reputations for example; but if supply and demand are becoming 5:4 in the future as a new player come in with zero feedback, the experience for the new player could be different. 

Too many red flags?  

I sent an email, but it came back as undeliverable.Is this a red flag, and should I move on to other applicants?

If total, then you'll be in the red.