Why did he poo on the floor?

my male cat has his own room for his toilet, its the spare toilet big enough for him, he has a large litter tray too, last night i popped my head in the room and it needed blitzing, so cleaned out the tray and washed it, i took up all the litter from the floor swept it all, and scrubbed it all with soapy water, dried it...dried his tray, put fresh litter in it and the room was nice and clean and fresh and nice to be in...this morning I went in and he'd scrapped all the litter to the left side of the tray, peed on the bare tray, and done his poo on the clean floor..I dont get this cat I did everything to make it pleasant for him and he messes on the floor??..did he not like the clean smell!?