I have the same problem with my wife.
A while back when the DC40 was the Vacuum I was using, I came home and the cable was just hung over the handle and the cleaning head was clearly wet... She never ever does any cleaning but this time she thought she'd use it to suck up some tea she'd spilt on the carpet. I couldn't believe it, honestly I mean fair enough she attempted to clean it up instead of just leaving it like she normally does. But who would actually think that a Vacuum cleaner would clean some spilt tea up?
You see, my Wife is not only lazy, but also has no care what so ever for the items we own. I work very hard for what we have, and she thinks they just appear I'm sure of it.
I like a clean and tidy home, and if you keep on top of things like dust etc. Then it's simple to keep things tidy but she never cleans up after herself in the kitchen, never picks any of our Daughters toys up from the living room floor.... Oh the list goes on. I have been way before and come home and honestly you'd think our home would be in one of those TV shows where they clean out lazy people's houses because they're super dirty....
So don't worry, I'm in your boat.