I'd make a photocopy of the student's driver's license or passport, and I told them that this is a contract between me and them and if they break the contract, it would be them getting sued, that they were responsible as an adult with no parents involved. 

Living with friends here and there.Applicant 4: suspicious and issues already...supposed to be 5 adults 2 kids...only 4 applied...the daughters boyfriend the parents told me about living with them is suspiciously missing as an applicant.

And, while that might have been worth discussing had they approached you as "adults," they chose to financially harm you. 

But I bet you won't because instead of being a man and calling me and having a conversation like adults, you would rather belittle someone half your age on social media.

Yes, all adults get to be screened before moving in. 

.- An income to rent ratio over 3:1- Passed criminal background checkIt's a 3 bd/2ba property and the applicant is a single adult.

As soon as she was a day late you should have started the eviction.... start it tomorrow, you'll feel much better.You OOS Investors need to learn day 1 that Detroit tenants will F you in a second - they know the system and are good at it... old, young, male, female. 

Credit and background search each adult tenant that will be living in the unit. 

Is it the male or the female making the money?  

I've told countless groups of roommates: "It's time to be adults, figure this out and I'll be back next week to see how it's going".