I have been very fortunate with all of our cats over the years. This has NEVER happened to us. But I'm wondering if we haven't had it because our cats have always (with the exception of Shrimp Boat, who refused to go outside) been allowed outside access??? I am not advocating allowing the cat outside. We have been very lucky in that regard. We have two litter boxes in our house that rarely get used, but they do use them when they are inside for any length of time (cold weather, we are away overnight, etc).

I would rule out any health issues first if you haven't already done that. Try to neutralize the odor using Nature's Miracle or some similar product, and perhaps, introduce one or two more litter boxes and make sure they are "inviting".

I certainly understand your frustration, but don't let it sour you on cats in general. This is not a usual occurence. You may even have to isolate the cat to one part of your home. We've had to do the same thing with our dogs since moving into this house because one of our Goldens decided the living room carpet was her new potty. We blocked her entrance, had the carpet cleaned professionally and deoderized and simply haven't allowed any of them back in that area of the house. I know that restraining a cat is tougher because simply gating an area doesn't work. Perhaps you could have the couch professionally cleaned and replace the stuffing in the cushions to get rid of that odor for once and for all.

I wish you good luck.