I just now saw this thread, and wait! I
moved my MIL and cleaned out DH's dad and step-mom's house - why is someone else taking the credit?
Seriously. MIL was supposed to have everything packed, and "there won't be much." What should have been a two or three-hour event took all day, with us packing while she went through family photos, checked e-mail (she hadn't even unhooked her computer), etc. We didn't help unpack, though - we basically deposited the boxes in her new place and said, "It's a long drive home." Hot showers were in order when we got home, because the old place was filled with rodent droppings.
The dad and step-mom's old house was worse. They never
threw anything away. They'd moved out of this house 12-13 years previously but retained ownership and did not rent it out. There were old 2-liter soda bottles, chip containers, candy boxes, etc., all over the floor. You literally could not see the floor; garbage was 1-2 feet deep in places. And you could tell by the package styles that they were still there from when the couple lived there years ago. No mental illness; it was sheer laziness. The feminine product I found had not been used, but it was open. And there was cat and rat waste everywhere.
On both occasions, I wanted to leave, but there are some things we (DH and I) do - well, just because. (He's the most efficient/willing to help family; I help for his sake.) But according to the PILs, I'm The Best DIL.