Probably twenty or more years ago, some author with a c-name, wrote the burglar series, anyway, the burglar's lesbian groomer friend in one of his books, had one cat locked in the closet when he came over. He said, he had never seen this cat.
Her response was, if you have one cat, ok. two cats, still ok. When you have three cats, suddenly your the lady with cats -- not ok.
There is a perception about how many animals is too many animals, but it really does not have to do with hoarding.
My house is a mess -- messy, that does not make me a hoarder. If I had dog poop and urine everywhere in the house, THEN I would probably be hoarding and not just a slob.
Hoarders, cannot SEE when their animals are suffering, either skin problems, grooming issues, lack of body condition. They also do not recognise the urine and fecies in their home.
I mean, I have two x-pens in the room with doggy doors to the outside. If one of the dogs in those areas, rolled in something nasty, I know it right away and have to seek and destroy. Hoarders do not notice the stench, festering wounds, matted hair, curled toenails, sometimes dead dogs laying in rooms. It is a terrible illness.
A puppy mill person could actually leave their dogs in small cages, with poo build up, underfed with skin conditions due to poor nutrician or hygiene, but that does not make them hoarders. It makes them criminals.
So there are really two questions, what is a hoarder? and how many is too many? or When is enough enough.
People can be overwhelmed by the number of dogs, without actually hoarding. I think that people who continue to live with an overwhelming number of pets, are setting themselves up if they are prone to become hoarders though. One good emotional shock can do it if the propensity for hoarding is there.
My grandmother was a hoarder. She had paths through her house. There were five couches in the living room we did not know were there. She had 28 full sets of dishes in her dining room. And tons and tons and tons of everything else.
Thankfully, she did not hoard animals.
I think animal hoarders are the worst, because of the suffering to the animals, and the unhealthyness of living with urine and fecies.