cat peeing and defecating on couch

Question
My parents have two adult cats and they gave us their used leather sofas.  We took in an abandoned cat for a couple of weeks until he urinated on my sofa and my boyfriend!  We took him to the shelter and adopted a second cat (even had him declawed and got his shots up to date.  We have had this second cat for about 1 month or so and we just recently went on a three day vacation.  Our first day back I noticed the cat pooped on the sofa.  I scolded him and he hid under the bed.  The next morning my boyfriend found more poop on the other sofa.  We again scholded him and he once again went into hiding.  Today my boyfriend found more poop and I put him in the kennel for most of the day.  I have a six year old and a 10 month old who adore this cat however my apartment now smells like a farm!  COuld it be from my parents cats and our cat smells them?  Could he be mad at us for leaving him alone for 3 days?  We also checked the litter box and it is spotless!!

Answer
What are you feeding him that he is pooping so much?
Sounds like he doesn't like your parents taste in decor.
Did you forget to leave the tv on while you were gone for three days? Did he have to lounge on that used sofa and stare at a blank screen?
Now that your apartment smells like a farm, your cat will feel right at home.

Seriously, any leftover smells from previous cats can be stressful. Especially if you didn't use some sort of cleaner (to get rid of the smell..like the kind made for that at a pet store) to him the entire apartment smells
like cats everywhere!  Maybe start by thoroughly cleaning
all the areas where previous cats pooped/peed/hung out.
Even shampoo your carpets (you can rent a steam cleaner for a day for 20 bucks)

THEN.. look into the Feliway products available at the pet store  they have plug ins that release pheromones that say to your cat "hey, its ok to hang out here" they also have
sprays to use in areas where your cat goes to discourage
him from doing it again.

Also at Petsmart is a litter called Cat Attract that does what it says..it brings your cat back to the litterbox.

Sounds like this kitty is really stressed. Play some elevator music on low in the background or a mundane talk radio channel. (seriously) as this is relaxing too

My one friend claims that the Glade lavendar scent plugins
are good. In aromatherapy, the lavender scent is used for relaxation.

Also make sure the kids aren't at him constantly. Cats like to sleep up to 18 hrs a day and they like a quiet
place they can go to that says DONT BOTHER ME. Maybe
you have an area with a window he can perch in where its sunny and quiet and make it off limits

hope these ideas help