I also think Colton is probably completely different when he's not on camera or on Survivor. In those situations some people excel, which is why they get picked to go on the show in the first place, and some would fail utterly (like myself!). Usually they are pretty good at picking out the people who will excel or at least remain their boring selves (e.g. Katie), and avoiding casting the people who just wouldn't do well on camera or on Survivor, for whatever reason. The quitters are the times that they have failed.
I think it's funny that the person who drew the rock was such a non-entity to begin with. We won't really notice her absence on the show, and not even Katie herself seemed to care all that much.