When I tell a client I think they have a good case that means I think I have a shot at victory.
When I tell a client they have a challenging case, it means I love a challenge and taking on a case that others are quick to write off. That is simply how you can distinguish yourself in this industry.
Don Neuwirth, a student at Boston University in the early 70's once described how to play pinball saying it was not the meat, but the motion. That is somewhat akin to the finesse required to the conducting of effective criminal defense.