To those who answered my post in the beginning, many thanks. I got sane again with confirmation that I was not being unreasonable to expect 20 yo SS to be a contributor and respect the household.

SS's been spending the night out. Great. That means there's no manwhoring going on in my house at least while I am there. Kitchen, miraculously reasonably clean after his hearing something never heard before under his roof (me and DH arguing about SS) - a woman standing up for herself and refusing to tolerate the bs. I don't advocate having a home full of dischord. But, that needed to happen. I know it can't be expected to last, but then neither will this visit.

Again thanks to all, and I will try to be of service in the pay-it-forward kind of way.