This is a business.

Its easy to get wrapped up in wanted to learn everything, and it ends up in people losing sight in what their original goals were from the start. 

Tell people your policies, send them via email when they start the screening process, and send them again with your denial.

I'd suggest you ask as many questions as you can, there are a ton of people on here who are knowledgeable in many subjects. 

She moved out exactly a month if stay there and they left the place filthy also her son is not on the contract and I been told that many of them were living there while contract has only two people.

The few people I've talked to don't really have good opinions on it. 

The other is a smaller operation which does a lot of business in the specific neighborhood the house is in.

People?

You cannot maintain a business with negative cashflow. 

You have every right to be outraged at the offending party and that's the tenant.Stay focused on what matters and that is getting back in business.