It is usually very easy as the vast majority have terrible credit, criminal records etc. 

Does your background check system include a credit, criminal and eviction check? 

I hope you don't take offense to this, but you've put the cart well before the horse.

That is silly, you could be losing a great tenant.What you really need is to not only check out the property, but you need to check out the tenants too. 1. get the info proof of their past payments, 2. verify their ability to pay just like an new tenant by usual stuff like job, income. eviction, criminal record, and social media. 3.

Criminal penalties of up to $1,000 per misclassified worker and 1 year in prison can be imposed as well.

No offense here but you need to get BOTH sellers on the same page first.

The apartment manager wanted to cite for her CRIMINAL TRESPASS.

I'm not familiar with Cali but if the s/l was 4 years for contracts and unsecued notes I'd put my money betting on 4 years.I'd weigh the option of proceeding regardless of the s/l as the borrower would need to bring that as a defense, I'd bet they don't if no payment was ever made.Another issue, if a payment was never made it sounds like mortgage fraud that is another category getting to criminal charges, the s/l will be longer, 7, 10, 12 years, not sure, it depends too if the original was an insured lending institution or a private individual.It also depends if the note was generated from an installment sale or was made as a cash loan, purchase or refi.It will also depend on whois in the property and if the property has been sold over the past 16 years, we just had an example of a subject 2 deal going sour with subsequent sales and that can limit your security if the note holder fails to act in a timely manner.Frankly, I wouldn't fool with this one, 16 years old, foreclosure notice gievn and never followed through, that's pretty much allowing the note to go stale and abandoning the claim of the amounts owed.If the maker of the note is still in the property and you can contact them by phone or in person, you might be able to negoiate something holding the fraud claim over thier head, forgive some of it and modify it back to life, but they need to agree and you can certainly bluff your way along to a point.

He checked her criminal record online and went with the referral he had received.I would ask for references and check them out.

Ideas to consider: Some sort of splash screen like you get at Mc'Donalds regarding liabilty and whatnot so you don't wind up in court if the tenant uses the service for any sort of criminal or fraudulent activity and change the password once a month or find some other way to deny service to people when they are late on their rent....