A dog who is using the house as the bathroom just hasn't learned that he's doing a natural thing (eliminating) in the wrong place (on your couch). A dog is naturally a clean animal who will keep his sleeping area free of bathroom smells. You can use this to your advantage by monitoring his behavior and not allowing him full access to the entire house without your presence. You can condition him to go outside to pee, but it will take some consistent behavior training on your part to teach a stubborn dog new boundaries. Once you teach your dog that the whole house is his sleeping area, he'll stop making those nasty messes. Any dog can be trained, it's the time it takes to be consistent and vigilant on the owner's part. Here's how!
How to Train a Stubborn Dog That Wont Potty Train
How to Train a Stubborn Dog Who Won't Potty Train
Start over with your dog. Pretend he's a puppy. When you leave the house and can't watch the dog, first have him go to the bathroom outside, then bring him in and put him in the crate, or keep him fenced off with a baby gate in a small area of one room. The smaller the area, the better the chance your dog will keep it perfectly clean.
Don't leave for more than a few hours. When you get home, immediately let him go outside again to go to the bathroom. Continue this method every time you go out so the dog is never left free to make a mess unattended.
When you're home with the dog, make sure he's in the same room as you. If he gets up and wanders off, let him go outside to the bathroom. Installing a doggie door can make this process insanely easy. Your dog will go outside automatically.
Never let the dog wander off into the house without you there. Always let the dog outside as soon as he gets up and leaves the room. This will train him that the place to go to the bathroom is outside.
At night, keep the dog blocked off in the bedroom with you. He will learn to lay down and stay in the room without eliminating.
If he has a real problem, crate him or block him into a small space to lay down. Gradually increase the size of the space you allow him as he keeps it clean.
In the mornings, let the dog out immediately when you get up, going directly to the door. You will be training him that going outside is his only choice.
Go outside and praise him when he goes where he's supposed to go.
With consistent supervision, and restricted access to the house, you will be setting your dog up for success. Dogs are pack animals that want to belong to the pack, and with your guidance, your dog will no longer have the chance to be "stubborn" about housetraining. Once you teach him the places that are "good" for elimination, and take away all the unsupervised chances for him to fail you, he will magically learn a positive new behavior from you, his trusted leader.