I'm not trying to say 'nananana' but under this regard - I'm so glad I don't live with Adrian anymore. He knows it and I've told him too, numerous times, that he is a slob. :(

You need to tell him straight when you want him to help or let him know in advance, plan for it, make plans with him to clean. Or when it comes due and he's not there, just tell him to get off his butt and give you a hand like he said he would. You need to be more direct when you need him and don't allow him any reason of why he shouldn't help. Period. "Now, my dear, it's time to clean." Yup.