I had a cat my vet gave me one time that stayed hidden all the time. She had been brought in to be PTS and the vet knew I was a sucker for a sad story and I ended up bringing her home. I wonder if their former owners broke their hearts by getting rid of them and their grief is just something they never overcome. Princess, that I brought home from the shelter stayed hidden all the time at Kevlins after he adopted her and I have always felt like she grieved herself to death. These babies are far more senstive than peole realize.