I think there certainly are some difficult clients as some people are just plain difficult for just about anyone to deal with, and the ability to deal with difficult clients is hopefully something competent therapists can do. But I suspect as in all things where personalities may collide, a bad mix can lead to a bad therapy situation. (I am in NO way saying that bad therapy situations are always due to a bad mix or in any way the client's fault. I'm just saying that sometimes despite skill and best intentions, personalities will collide and lead to problems.)