Oh, 6 years old isn't a puppy anymore, so that can't be his excuse! For the couch, I'd suggest a nice slip-cover (gold-colored to match his fur perhaps?). Have you tried the "spray with a water bottle when caught" or the "soda bottle with pennies in it that makes a bad noise when thumped" approaches when he is caught? The water bottle may not work, some retrievers view it as reward, not punishment ... There are sprays that theoretically make things "taste" bad, but I don't know if they're okay to use on absorbant stuff like pillows, or what they'd smell like to you ...

Any ideas, anyone else?