inappropriate defication/urination

Question
we have a male and remale sibling cat situation. both bottle fed from birth, spayed and neutered at young age. litter trained and very affectionate. Dont act like cats. ages-7years. the last 2 years found inappropriate urination in various places in house. mostly near windows. use indoor invisible fencing due to persistant soiling. now, male cat has begun to deficate,very frequently, in our bathroom sinks. i have tried all types of sprays to keep pets away. nothing seems to work. they have no front claws so i think outdoor living is out of the question. do you? also, even if they can go out, will they adapt at this age since they have never been out? we are at our wits end and they are destroying our home.we love them so much and want to keep them if possible. thanks for your advice

Answer
One of my neutered males, also 7, likes to poop in the big tub in the master bath. Needless to say, he tends to be banned from the room, but he can be a sneaky one (and despite having a plethora of litterboxes, too). Someone (haven't been able to figure out who) also pees against the windowsill).  Even though my cats are indoors only (and are terrified of going outside, since it usually means either a trip to the vet to have their temperature taken (which is the only thing they remember) or a cat show (which means lots of baths), the peeing against windows could be their way of marking their territory, even for the neutered ones.

This is one of those questions in which I have to say that I am going through the same thing, and if ANYONE can figure out how to stop it, then please let the rest of us know.  

I clean as often as possible around the windows with a bleach solution to at least get rid of the previous scent of ammonia/urine, and I've tried sprinkling something that the cats seem to dislike (this month is Pepper).

For the pooping in the sinks, we've run out of ideas why until we figured it could be that despite the fact that the sink to us looks clean, it could have a residual smell that the cat finds similar to poo (gross, but anything sounds logical when you're at wits' end). At one point we placed trays on top of the sinks (and no, they didn't poop on that), and now just work to keep the sink really clean.

These actions work for our idiocyncratic bunch of cats; maybe some parts will work for you.

And at the age of seven, I don't think that having them live outdoors will help, but might cause them to bring in ticks, fleas, other diseases, or injuries, claws or no claws. I doubt it will stop them from pooping and peeing around the house.