As the wife of an only child (a son, obviously) who is messy - I am too, don't get me wrong - let me bring a slightly different perspective. My MIL will come clean on occasion, as a gift. (this is once or twice a year) - but it is planned in advance, as she brings the carpet steamer with her. I appreciate her coming over but she does move things around and I can't find stuff for weeks after she's been here. I love her to death, and I let her clean b/c it is how she shows her love. With that said, I would never let my own mother do the same - I'd be too embarassed. I might have her come over and we could clean together- were there ever time for such a thing.

If my dear MIL ever came over unannounced and did what these parents did I would be upset; especially if she found things I had taken the effort to hide from my husband - like the little things I plan on giving him when I get pregnant, as a way to announce it to him. Would I go off on a profanity-laced diatribe? not a chance in hell. I can barely say damn and hell in front of my own parents. I think I've said shit in front of the in-laws once . . .my husband, however, can curse freely in the presense of his parents, he doesn't curse often, but neither does he hold back. Point being; it might not be uncommon for the LW to use expletives in front of his parents.

He went overboard, sure. But so do they. They should all apologize, hug, and he should ask for his key back and inform them he's changing his locks.