Attitude problems are only a perception and someone's personal experience of that person - hold no weight! Property management relies on legislation that cannot be overruled by bad attitude.
I would ask - how specifically?
My big concern is how, in a joint tenancy, does one tenant get breach notices and not the other???
I smell a personal conflict between the pm that provided the reference and the wife and would ask further questions to clarify.
Also what is "rental arrears", did it result in a breach notice? Was there an application to tribunal for a payment plan or vacant possession? What was the result? A tenant paying one day over their due date is technically classed as arrears - look deeper.