Since my first post on Roto-Rooter, I've called them several more times. Once to fix some work done my previous plumber, another time to get stuff hooked up in my new house and another time to fix a leak.
I can report they have consistently provided me with professional and pleasant service from the time I called to the end. They followed up to make sure I was happy with the service and asked for feedback. I asked one of the plumbers how they hire and train the employees, and he let me know that they are selective on who they hire and make sure they know the expected standards for working with customers.
I've used Roto-Rooter's service as example in several presentations I've given on customer service and have heard positive feedback from the experiences of those I've presented to.