Male cat born 1/10/04 (so he's five months old now.)  I got him about 6
weeks ago from a shelter.  He had been an indoor cat and had lived with
his mother and siblings.

From the very first day he would go into one particular corner of our
downstairs powderroom and sh.t on the floor.  With two exceptions, he
has sh.t on that same place every single day since.

He is our only cat.  Our former cat (a female) never used that bathroom.
 The construction is new.  It's an inside corner.  He was not
constipated when we first got him - on the contrary, his first few poops
on that floor were runny.

Here's what I've done to try to stop this.

I wiped everything down with the enzyme solution.  (I do this every time.)

He had a litterbox upstairs, but I put added a litter box in that room.
 It doesn't fit in the corner he prefers, but it's about three feet
away.  He pees in it, but still goes to his favorite corner to sh.t.

I bought a little litter box and put it in that corner.  He sh.t in it
once but then started sh.tting in front of it.

Figuring it was too little, I squeezed the big litter box into that
corner (it really doesn't fit there) and the cat went in there once but
then the next day went behind the toilet to sh.t as close to that corner
(outside the box) as he could.

I blocked it with a waste basket.  He sh.ts in front of the waste basket.

I got him neutered.

I locked him in a room upstairs (with food, water & a litter box while
he recovered from his neutering.)  He whined piteously to come out.
When a kid gave in and opened the door he made a beeline downstairs to
sh.t in that corner.  He didn't even use the litter box in his room
because we had taken out the clumping litter while he recovered from his
surgery and he won't use any other kind.

I clean all three litter boxes at least once a day, often times more
(following along behind him picking up his excrement where-ever it lands.)

We've tried three different kinds of kitty litter besides clay:
Yesterday's News, a cedar type and a wood pellet type.  He will only use
the horrible toxic clumping clay kind.  (I'm getting these fumes in my
pores from cleaning three boxes or more a day.)  He'll use the other
kinds only if we cover them with the horrible toxic clumping kind.

He is the sort of indoors cat that makes a bee-line for the door
when-ever it's open, then stops just outside and makes us fetch him
back.  (I hate that.)  But thinking maybe he wanted to sh.t outside, we
let him outside for a supervised visit to the shrubs.  No actual
sh.tting was observed, but he was out of sight and we assumed he did.
Later that day he found enough in him to manage a small sh.t in that
same corner.

I've got three small children and making our downstairs powder-room
inaccessible to a cat isn't very feasible.  Frankly, I'd rather give up
the cat than the bathroom (which is new construction to the tune of
$20,000 and desired long before the cat was thought of.)

Can anyone tell me something else to try?

Would I be a horrible person for returning this cat to the shelter?  I
run a business from my home and the constant waifing of cat sh.t from my
powder-room is making me sick.

Dally