Vet the contractor (license, bonded, insured, no criminal history) , do NOT pay them ANYTHING upfront.

We typically like to meet your pets at some point in the process, too.Our tenants’ safety and the peaceful enjoyment of their home is important to us, so we do a credit/criminal background check on all applicants aged 18+.

I also have updated my application with a section where they can address variances to my "typical qualifications," where they can explain things like an old criminal background record (still states absolutely no evictions) or a divorce that wrecked their credit score. 

Have a degree in Criminal Justice, life experience, and currently still active duty Marine.

You can reject a Section 8 applicant for the same reasons you reject other applicants: credit score, Landlord reference (or lack thereof), criminal history, etc.

Criminal background: No violent felonies within the last 7 years.

I notice that most of the examples of references "saving" someone from making a bad decision on a tenant involve instances in which the problem would have been detected with a simple background, criminal, or credit check.  

If she has no evictions or criminal history that is great.

After all, if criminal behavior is the culprit then why not advocate for prosecution of criminals?

Basically after we mutually agreed that she would leave after two weeks we discovered her criminal background through a reverse phone lookup.