Over the years I have worked with umpires who had different skill levels and have learned to 'work with them'.
Having said that, I always inform the assignor I will not work with certain people. When asked, I will give the explaination as to why. Sometimes it is personality, sometimes it is skills. I have worked with umpires who look for a reason to eject and I have worked with ones who will not eject on any grounds.
I work for 4 assignors and try to be as honest as possible at all times.