Standard qualifications (no smoking, 3X rent, criminal/past history) and not allowing pets at this time.

Also is it worth it to seek civil or criminal charges against them?

Afterwards, I further my criminal justice career by becoming a US Secret Service Police Officer.

Not everyone can purchase a firearm, either due to past criminal history, age, physical location, or what have you.

Appfolio charges $20 for a full credit/criminal/eviction back-round check.

Aside from providing the basics (ie. listing tool to get the property published to 10+ major sites, scheduling tool to schedule viewings, tenant screening with comprehensive applications -- pulled reports from TransUnion, which include nationwide criminal background checks + credit checks + eviction history, digital lease creation tool, rent collection tool), automated maintenance tracking is key (and having everything in one spot makes a world of difference when it comes time to have a contractor come in and make a repair).

It heavily relies on a market rife with criminals. 

Graphic Designer both have very little debt Both have clean criminal ect...And have been in their current separate rentals for over 2 years each.  

There are a lot of great options out there; aside from providing the basics (ie. listing tool to get the property published to 10+ major sites, scheduling tool to schedule viewings, tenant screening with comprehensive applications which include nationwide criminal background checks + credit checks + eviction history, digital lease creation tool, rent collection tool, and maintenance tracking tool), some services also offer your tenants additional capabilities which makes it an easier sell on your end when getting them to transition over (ie. their ability to report on-time rent payments to the credit bureaus; this can create an added incentive for making sure they pay that rent on time).

As 27% have criminal records.