Teresa Nielsen Hayden has put together an amazing, comprehensive post about squalor and animal collecting: the so-called "cat ladies" and garbage people. The stories are incredible, the syndrome pervasive. People across the country accumulate hundreds of animals, or fill their bathtubs with feces, or stack newspapers to the ceiling in room after room until their homes are uninhabilitable. Sometimes, these places end up so far gone that they have to be bulldozed after their owners die or are institutionalized.
To me, the most striking feature of the animal hoarder's psychology is their state of complete and utter denial. This is not your usual "Your father never did that, you don't understand what he was going through, and why do you insist on only remembering the bad things?" kind of denial. This is world-class craziness. Hoarders insist there's no problem, the house is just a little messy, and their critters are fine–even when the feces are literally a foot deep, animals are dropping dead and other animals are cannibalizing them, or the poor beasts have chronic infections that leave them with masses of scar tissue instead of eyes. If it weren't real, it would be unbelievable:
Irene Holmes, a District Attorney who has assisted in the prosecution of a number of collector cases throughout the United States, … states that collectors have a "death grip on denial." She gives the example of a woman who was shown a photograph of one of the dogs that was seized from her care. The photo shows a Weimaraner, so starved from lack of food that it was literally shedding its intestines and rectum. Holmes relates that when the woman who owned the dog looked at the photo, her only comment was "I guess it did seem a little ill."
Their recidivism rate is close to 100%.