Unfortunately, I have known a cat hoarder. My little sisters (age 9, back then) told me they had a neighbor who had, in their words, "like 90 cats!!!" Being imaginative 9 year olds, I thought they were exaggerating and the real numbers were around 5-6. I asked their (adoptive) mother about it, who told me that the woman has about 30 in the house and even more are "outside cats". She said that the entire neighborhood thought it was so funny because she dumps an entire bag of cat food on the ground and then rings a bell when it's dinnertime and all 40+ cats who live in the small area around her home come running to get their dinner. Everyone in the neighborhood thinks it's so funny to see a herd of cats running at the sound of a bell, and they just call her "the crazy cat lady". She said that a few of the cats are run over every year because people speed down their 'country road'... I visited and saw what was up for myself... cats were fighting over the food, many had injuries or an extreme amount of fleas, and most of them were not neutered or spayed. I couldn't believe that an entire neighborhood knew about this situation and thought it was funny and cute. My local animal shelter intervened, eventually.
I think in recent years, animal hoarding has been in the media quite a bit and so maybe one of the neighbors would have spoken up, had it been a little bit more recent... but it really concerns me that such a large group of people were so ignorant of the problem.