My FIL is like this. I think he is depressed since his wife died and he just doesn't care -- plus they both had hoarding tendencies. He gets a TON of political mail asking for money, and although I've gotten him to (mostly) not contribute, he reads it all carefully and then puts it in a pile to read it again.
I go over there every week to sort through his mail and file the important stuff. I sometimes sneak the political and other junk mail into the recycling when he's not looking. I hate to be so sneaky, but I feel I have to.
The floor in his living room is piled with magazines and newspapers that he hasn't read, but he won't toss them. He can't vacuum because of all the piles.
Also, I found out he hasn't washed the sheets on his bed since his wife died, 7 years ago!! (got them washed now.)