These are people looking for houses on their own, not represented by a realtor, and usually they don't have the best credit situation.

Probably should consult an attorney or at the very least, the agent who represents you for your health insurance.

For most sellers who own the property cash, it represents a substantial part of their overall savings. 

Go to their agent and they will have you sign paper work acknowledging they are represent you as well as the seller.

or does this represent that the current owner has no mortgage?

Some attorneys help with things like operating agreements for LLCs that hold the properties, some specialize in commercial contacts, some specialize in evictions and representing landlords, and some do a little of everything but nothing really well but work well if your needs are simple.  

@bashir badu,Another option,If you don't have an exclusive agent representing you,Consider reaching out to top multifamily commercial brokers directly and let them broker the deal, you'll get their attention since they'd be getting full commission. 

I particular I have (based upon the advice and input of others) created a Screening Criteria with scoring to help applicants know how I select the most appropriate renter as follows (please advise if you think I should make changes):Rental Application Screening ReportInterview: House showing: Walk-through of property: In person 5 pointsUsing licensed realtor representative with FaceTime or equivalent 5 points Using licensed realtor representative without FaceTime or equivalent 3 points Other: 0 points On time for appointment: 5 points Running late, called to inform: 3 points Late: 0-10 minutes 2 points 11-20 minutes 0 points 20+ minutes- landlord leaves, applicant rejected Respectful and courteous: (subjective, score -5 to 5) To landlord: To each other: *Cursing, swearing, pushing, shoving, and violent behavior, demeaning speech or treatment of landlord or landlord’s agent or to one another: Applicant rejected Neat/Clean appearance of all parties: 5 pointsApplication: Filled out application entirely leaving no blanks: Yes: 5 points No: -5 points, grounds for rejectionPaid for application fee?

I think he can just counter with refusal to do the work if buyer does not agree you have no contract.I am assuming these request are coming on repair addendums and he has a competent Broker representing him..

The following is NOT legal advice.That said, the tenants will need someone who can represent them legally and sign documents in their name.