Most COs I knew were decent sorts. Maybe it was because our congregation was the model congregation for our area. Maybe it was because I had few theocratic ambitions, so the COs required nothing of me.
One was the complaining discouraging type who insulted me. Later I found out from his wife that they were both tired out from the work (they were very elderly) and were very depressed as their next assignment was taking them away from their grandchildren. They wanted to stay in our circuit to be with their grandkids.
They quit shortly thereafter. stayed in the area, and he became a substitute CO. They seemed quite happy.
Another CO, Henry Ramsey, was a really good CO. He cared about people and his requirements were reasonable. We have relatives in common, so maybe that made a difference. He was also very honest. When I asked him how he and his wife remembered so much about me and my family after not seeing me for a year or so, he said he and his wife kept notes and reviewed them before they visited each congregation.