Our next-door neighbors had that problem. They lost their home and the new owner filled two commercial dumpsters, and made special arrangements with local trash pickup to make multiple stops to get the rest. It took him and a cleaning crew a week just to empty out the house.
Sounds like my experience.
I bought a house from an editor of a prominent daily newspaper, but there was one strange event in our first survey of the grounds: the realtor virtually body blocked me from going around to the back of the outdoor tool/garden shed.
I thought it was odd at the time, but didn't realize until after closing why: they guy had piles and piles of little lumber pieces, tin cans, gardening junk, half-full mulch and fertilizer bags, etc, all hidden in decaying heaps behind the shed. I'm talking 3 to 5 foot high piles.
I filled up an entire mid-sized dumpster with the refuse this guy left in the yard.
It was a the "Harry Homeowner" version of hoarding.