I’m not sure where to start, it’s your tits they got on isn’t it. Stripping the bed - reminds me of hotel staying, not a beautiful Christmas at their wonderful sons family home.
Putting the dishes in the sink, have they a double sink and/or dishwasher, because putting plates in the sink to soak for a few minutes either get rinsed in the second sink or straight to the dishwasher. My mum used to soak everything in the plastic bowl and then rinse it in the bucket, that was in the days of shared kitchens and toilets at the end of the back garden, no I’m not ancient, just from a very poor background!
You may have a point, they have never entertained anyone except immediate family, maybe you are opening up a new world to them, or maybe you are different people but in your own way - yet different ways - know how to keep a clean house.
Maybe the eating thing, get your husband to remind them that when someone enters the room, in polite society we always stand, something we forget occasionally, the sane with eating, we all start together,