soberups
Pees in the brown Koolaid
There is an old saying..."never pass up a golden opportunity to keep your mouth shut" and I would suggest that the OP take full advantage of this opportunity in his dealings with the customers on this route.
We are responsible for our own actions, not those of another driver. It is unprofessional and inappropriate for us to take sides against or offer opinions about the behavior of another driver to our customers. If they aren't happy with his/her service it is their responsibility to inform management, and it is management's responsibility to respond to it in an appropriate manner. It is not our responsibility to get involved in any way.
We are responsible for our own actions, not those of another driver. It is unprofessional and inappropriate for us to take sides against or offer opinions about the behavior of another driver to our customers. If they aren't happy with his/her service it is their responsibility to inform management, and it is management's responsibility to respond to it in an appropriate manner. It is not our responsibility to get involved in any way.