Also speak to the banks involved in those deals.One last and often overlooked but super important step is to conduct criminal background check as well as run the credit report. 

They might be afraid if it's a scam or criminal.

Though the neighborhood could be a slightly criminal one, i.e. not the ideal location to raise a family in a peaceful environment, if you get the idea.  

A couple (with three children) would like to move in, but the wife stated that she would be the primary applicant and would not provide any information other than income for her husband (no background/criminal check or credit score).

BTW the state said they can issue fines of $5000 for brokering without a license and that does not include criminal charges.

-Tell them what your requirements are upfront (3x rent, credit/criminal check, landlord reference, paystubs)-Tell the tenants "Please text me an hour before to confirm you're coming"-If a tenant does not text me (rejection)-If a tenant shows up late without giving me a heads up (rejection).I spend 60 minutes a week showing a place.

Basically I have them submit some paystubs, I confirm employment and residential history and I use SmartMove for criminal background and credit check. 

I can't bring myself to use the word "right", because he's a criminal and should be thrown in jail for trespassing on the property.

I do run a criminal background check/eviction check so that I know what to expect.

What they are doing is transfering criminal penalty risk exposure to YOU.