My mom. She accumulates a sea of junk and old clothes around the bed and bedroom so you have to walk over it, an entire couch in the living room gets covered in clothes, boxes, and other junk, every table is cluttered, the floors getting stuff piling up too, from boxes and basins, stereos and used food containers. Kitchen clutter is bad enough that apart from the infrequent times when it gets cleaned (maybe once every few months or so), I'm unable to do any cooking there, and dishes may sit in the sink gathering mold for weeks on end. That was more in my teenage years, though. She always buys compulsively these cheap trinkets and wares from discount stores, filling the house up as if it boosts her in some way to have a multitude of worthless things as opposed to saving up for a small quantity of valuable things.
The worst was at our last residence before packing up across country. It accumulated over 13 years, but she's doing this in the bigger space they're in now as well. I'm a neat-freak, needing everything tidy in order, but since my first go at university I had to leave during a major depression during which I stayed in the dorm for a few weeks straight, failing to even brush teeth, she thinks I hoard things too. One sister saw how I kept the room the next year when leaving though.
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"There are things you need not know of, though you live and die in vain,
There are souls more sick of pleasure than you are sick of pain"
--G. K. Chesterton, The Aristocrat