Process comments, "I'd be really interested to know whether the cleaning thing is the result of institutional living or whether he came from a clean home to begin with. Also, I wonder if it will fade as he lives longer in your home (not because you're "slobs," as you put it, but because he may still be trying to make a good impression.)"
I'm curious about the same thing. I may ask him how tidy his stepmother and father are. I don't know what that home was like. Given his comment to his father I am assuming it was kept more tidy than our basement -- although our basement looks like it is the home of adolescent boys. When I was at the group home, which is a rennovated house, I was impressed with how clean it was. When I was there on Saturdays all the boys were busy cleaning and looking like they were managing to enjoy themselves while doing it: lots of joking and some degree of competition.
We made the downstairs bathroom his "weekly" chore. That is in quotes because how he schedules it is entirely his decision. As long as he is keeping it clean, he can keep that as his chore. He is not, by the way, expected to keep it as clean as he made it, and if he gets tired of that as his chore he can have another less onerous one. He insisted that he was happy to take it since he couldn't stand to use a filthy bathroom and would clean it anyway.
But either some of the cleanliness is about impressing us, or we are rubbing off on him. A few days ago I noticed a dirty bowl in his bedroom. I didn't say anything about it because I wanted to see how long it would stay. It is still there. There are also a few dirty clothes on the floor and not all the dresser drawers are tightly shut. Oh, he also never makes his bed.
So he isn't freakish or anything.