..... donned the biohazard suit and hard hat then entered the DS's bedroom to clean it (and on a Friday night too!!).
TaDa!!!
Actually it wasn't sooooo bad as he'd smoothed the way by binning lots of crap, tidying up a bit, and trying to sort things out generally and all without so much as a teeny tiny grumble.
Mind you, as he's in his early 20s he should be doing it himself 
Why do young men (and women??) never "see" the things they should be tidying up??
I'm now preparing for a roasting for doing it for him but, although he makes "attempts" I still have to get in there and sort it properly!