Build Relationships: They foster strong interpersonal relationships through team-building activities, ensuring team members know, trust, and respect one another.5.

You will also need to be interpersonally businesslike with people .

Do NOT offer to give them your key or you are just enabling their behaviour. 

Tell her that you are having problems getting the repairman there because of her behaviour and that you will be there when they are there.

While I would typically say stay out of interpersonal issues between tenants, this is obviously more of an actual problem bordering on or actually a lease violation.

You can also report the buyer's agent to their broker and the board if their behaviour was unprofessional.

A good reminder to have someone with good interpersonal skills to ask the right questions.  

. - Negotiation skills: Interpersonal communication skills. 

Had the tenant let you know after they got the January bill and the water company didn't work out a deal with them, I might pay 50%....but the tenant dropped the ball big time and I wouldn't reward that behaviour. 

Along with total amount borrowed, cash flow, length of time in business, business practices, Interpersonal skills and what makes up your assets, Etc...Good Luck!