Re: Why does my cat poop on the carpet?
Smir has a valid point...cats noses are very sensitive and a 'dirty' box will be off-putting. I scoop mine once a day, though some cat-housing situations may require a twice daily scooping of waste. Other things to consider: perhaps the cat does not like the litter material being used, the size of the litterbox is too small, the cat doesn't want to do #2 in the one he does #1 in...so having another box could resolve this.
The cat is unhappy with something, that is why it is not using its' litterbox. I also wish to stress: cats do not do these things to be 'vindictive' or 'calculating', they *do not* think that way. Unfortunately, doing these things is their only way of communicating something they think is bad, not right, unacceptable, awful and/or is having a medical problem.
I would give some of the suggestions a try and if none of the solutions/suggestions work, then I think I'd take my kitty for a vet exam to see what's up and if anything internally is bothering him.
Best of luck,