Actually, thinking about it, our main bone of contention is our cars, or more precisely my car - DH drives my dad's car, and because my Dad nicks it back again at short notice, DH keeps it pristine, and doesn't allow any food to be consumed in it.
But my car is a completely different story. Dogs go in it, kids go in it, and I have a terrible habit of collecting water bottles and pamphlets from aldi and lidl, and not putting them in the bin regularly. I have CDs everywhere, kiddies books for DS and choir music coming out of seat pockets, and dog toys and bowls in the boot, it's a typical family car as far as I'm concerned!
DH whinges about this, and fair play, I can see why! But then, whenever he does drive my car, he munches chocolate bars like they're going out of fashion, and stuffs the wrappers in every orifice he can find, including down the back of the driver's seat...! 
Add to that he fiddles with all my trinkets too - I have a little horse wind-chime that he hates, and always takes it down, stuffs it in a door pocket all tangled up, and then it takes me ages to untangle it and hang it back up again. He also gets annoyed at my cuddly teddy on the back seat, and dumps it on the floor. Then he wonders why I get pee'd off at that!