How I can even verify that the seller has this agreement in place and has the authority to sell the property? 

@Jonathan Anderson Like most others mentioned, looking at their tax returns is one way of verifying their income.

Tenant placement AND management is the best pricing, and since I have to deal with who we pick....especially now....I'm screening and verifying everything.Gotta have some skin in it, in my opinion.

@Conner Daniel, first let me preface this by letting it be known that I am not a tax professional so you should always verify tax discussions with a qualified tax professional.

Go D4$ and then use that list in Propstream to verify equity, skip trace, call, mail, knock on doors.

Without stable income (verifiable) I wouldn't expect any bank to approve a loan.

Lenders send appraisers out to the property to verify value.

They can verify a deal as good or bad, they can have local knowledge and recommend contractors and so on.

@Chris Abislaiman Yes I self manage and I run a background check, call their last two landlords and verify their income/call their boss.

They're the ones that need to verify what you'll need to get a deed if you buy it.