The idea that dogs cannot be on furniture came out of old dominance based ideas that are simply false. If you're comfortable with the dog on furniture then let him. It's a lot easier in the long run.

I find that no matter how comfortable my dog's bed is, the couch is always more comfortable with her, plus it means she's right next to her people and bound to get belly rubs! Personally I LIKE my dogs on the furniture.

I have no suggestions on how to train a dog not to get on the couch. I've never had a reason to train that (and in fact, I had to train my dog to get ON the furniture!).

Doubt it very much! Dogs (almost as much as humans lol) do what works for them. If a behaviour is rewarded (in this case a warm comfy place to lie, perhaps) it will be repeated.

Who knows why he prefers the sofa - previous learning, comfier than his bed or perhaps it is that when you are not there he can lie on the sofa and be close to your scent. Perhaps it makes him feel safe. And then in you come cross about him being on the sofa and he thinks 'what the heck?'

And then to compound the problem you use an aversive like the pet corrector. So now he has you cross and the fear induced by the compressed air going off. But not always - sometimes you reward him. Look at it from his point of view - you ask him to get off the sofa and immediately give him a treat. Have you rewarded him for being ON the sofa? Not from your point of view, but perhaps from his?

If you want him off the sofa give him an alternative behaviour - as suggested - 'go to your bed' or 'come to me and sit' or teach him a hand touch. He touches your hand (well away from the sofa) before rewarding him. You need to separate the actions of being on the sofa and being rewarded.

['Touch' is actually a very useful cue for moving any dog around. In and out of the car, over an obstacle on a walk, off the sofa (because he definitely needs to understand that he can't always be on there. If you ask him to get off, he needs to get off). I would also suggest that you do some desensitisation work on his collar - you need to be confident that he will not react to you (or anyone else) grabbing his collar in an emergency.]

If you decide that he can go on the sofa sometimes, again as previously suggested, put a throw on there. My dogs have all been allowed on the sofa, the throw goes in the wash each week, not a problem. But the throw will also be his signal that he is allowed on the sofa. If you have visitors put the throw on his blanket on the floor, or in his bed. He can lie on that when you are visitors are there. He will soon learn that the throw is what he is allowed on and that will be his cue for getting on the sofa if he wants to and laying in an alternative location when you need him to.

Dogs do not set out to 'defy' us, they work very, very hard to understand what we want. We confuse them by being inconsistent