People like this are hoarders or collectors. Usually they're live animals, I've seen houses with 30-50 cats. One elderly gentleman's house was filled with newspapers and trash he had picked up such as cardboard and empty bottles. And I mean filled, you could barely move. We did see dead animals but not a collection. The strangest one was the retired teacher who had a dead horse in her living room. It's sad because most of these people are alone. But this woman had family who could have gotten her help. Although these are often elderly, there are cases of younger people who do similar things.
Reminds of those two brother bachelors in NYC years ago, who were found dead in a house littered with boobie traps and filled to the attics with stacks of newspapers.
She was always a little bit "off", but never so much so that the family could have had the superior court convene a lunacy board on her (that's what you used to do to get somebody declared incompetent). She was perfectly capable of managing her own affairs, she just conducted them in sort of a loony way.
My dad and his sisters eventually convinced her that she would be "more comfortable" in an apartment rather than her big old gloomy Victorian house . . . they had to hire a dump truck to carry away all the stuff. She didn't do animals, live or dead, but she had entire rooms stacked to the ceiling with old newspapers, just with little passageways to move around.
Sometimes the transition from "collector" to "eccentric hoarder" to "stark staring mad" kind of creeps up on you . . .
As for this case, I frankly would rather err on the side of letting folks manage their own business, until it becomes a health hazard (which was obvious in this case). It could be that she cut herself off from her family when they suggested that she clean things up. My dad is a master of tact, and it took all his considerable skill to get his great aunt out of that house. Not everybody is so gifted - they're not tactful, they get screamed at, and they decide it's not worth the grief. And given the state of the law nowadays, it's even harder to get somebody declared incompetent than it used to be.