NEED HELP

My roommates cat poops everywhere!!!
He is the only male cat in a big house with 2 female cats. We change the litter every week, and he has 2 litter boxes.
But he continuously enjoys pooing everywhere. Never upstairs, just in the basement where their cat room is and my bedroom. He love corners or in the rec room by the tv, just loves my bedroom. He enjoys pooping on blankets that are on couches, and my clean laundry. You leave a sweater on the floor in my bedroom, oh boy will he poo on that!
Hes a medium hair cat so after hes done a little left over piece falls off somewhere as he walks away.
All in all this cat is adorable, hes playful, he rarely gets bugged or angry, he play fights with the female cats but always wins cause hes pretty much twice their size, hes a nice cat very cuddly.
I Don't hate him, but my roommates will do nothing more then continuously changing the litter. I feel like there has to be a solution for this. or to get him to do it less. cause 2 days after the litter has been changed hes back to his old ways.
I even reward him and praise him when he does get it in the litter box or even if its just out side, at least he tired then.
But being the one that always has to clean up after him cause he only does this during the day or at night when no one is around. everyone goes to work and it gets stuck on me. I own the 2 female cats, never have problems like this ever and thats saying something cause my cat jazz is 19 and i have had her since i was 3, she pukes but i would take puke over poop any day.

someone please help me! I told them they need to seek advice from a vet or someone but then they get defensive and go back to the clean litter box excuse, we could clean it everyday and he would still do this.

[LindaTX]

He could have a urinary tract infection and the only way to know for sure is take him to the Vet.  Is he an older cat?  And has he, and they, been neutered and spayed?  If his litter box is clean (you said they clean it every week??), and kept clean, then it might help for a few days to keep him separate from the two females, maybe in a room or bathroom or laundry room to see if you can get him in the routine of using "his" litter box.

Maybe the other kitties are peeing in his box and he doesn't like it.  If he is enclosed in a room with his own clean litter box and still doesn't use it then I think he is trying to tell you something, like he is physically hurting.

[nancyjac]

Obviously, since he is doing this 2 days after a litter change, the boxes needs to be cleaned more frequently.  The litter boxes need to be cleaned daily, not weekly.  Cats are quite fastidious and he is trying to tell you that he won't poop in the box after 2 days of not cleaning it.  It is the equivalent of asking you to use a toilet that has not been flushed for a week.

[LindaTX]

Ah-haaaa....that's for sure!   Good analogy, Nancy!  ;)