In reply to TheDrunkenBakers:
Sort of home turf, this.
We had an empty nest for all of 7 months before the first one came back. Two years later the second one came back, and a year after that the third one came back (and then his girlfriend from Florida).
The first one (a foster son - not really, but it's complicated) gets charged rent at a near commercial rate which went into a savings account - he now has enough for his share of the deposit on the house with his girlfriend. He regularly had his rights read to him and is now properly domesticated (24 years old). We threw him out for three months as a necessary behaviour modifier, which worked and a much chastened young man returned.
The second, our daughter, keeps her room as a tip, but is mostly diligent around the house, cooks regularly etc. needs to be pushed in the right direction but is getting there. She's not paying rent because she understands how savings work.
The third, the eldest, has gone native as a long course student and an intern in the States. He is full of promises but nothing yet (he moved back in in early August). Rent position yet to be determined, but food bills to be paid. He's as domesticated as the horses he looks after as a vet. His girlfriend has taken the place of the cleaner and is diligent.
In our experience, point out the fact regularly that you are not there to look after them. As adults, they are expected to contribute substantially in one way or another as their means dictate. Point out that the standards are the same for everyone, and if they don't like them or feel able to sustain them, then they need to look for somewhere else, but in the meantime, the standards and their contribution will be maintained.
We have instituted a board so that we all know who's in and who's out each evening. If you're not on the board you don't get fed - more about expectation management and consideration than anything else. First one in starts cooking - going upstairs and hiding or flopping on the sofa in front of the Big Bang Theory is not acceptable.
Showers all now have squeegees in them and no shower will be left unsqueegeed. We are now adopting a tone of absolute expectation - covers the same problem as yours with bins (the food bin in particular being seemingly my job by default). No dumping, the dish washer will be switched on before it's stinking, cleaning up generally. It sounds a bit mean, but we've been running around after them for twenty years. Now they can deal with the bulging laundry basket (14 shirts last weekend). In our view, it's all part of growing up - if they can't cope with that then they'll not cope with the rest of the stuff life throws at them - best get into good habits.