If it's attention seeking behavior, such as jumping up to greet, trying to play when you don't want to play, whining for something....then ignore it because attending to your dog reinforces that kind of behavior.
If it's something where the dog is being reinforced in some other way, either by the environment or all by himself, ignoring it doesn't matter. The dog couldn't care less if you ignore him. He's already getting a kick out of whatever he's doing. So, you distract him and give him an alternative, preferrably an incompatible one, if possible. For instance, he's chewing your couch, give him a no reward marker, "eh-eh" and hand him a wonderful chew toy, praise and treat for chewing that instead. Better yet, prevent him from chewing the couch in the first place. Prevention is always better than waiting for him to be reinforced by the fun of chewing the couch.
When a dog appears to be "blowing you off," he's not thinking it through in a logical way like we would....."Well, she called me but I don't think I'm going to do it because even though I know it's 'wrong,' I really would rather be doing this." No....that's human complexity. Dogs do what is most motivating to them. Period. There is no morality in it to them. Whatever works best, they do. If you tell your dog to sit and he doesn't, he has not had enough practice. And as it was said, he needs practice in lower distractions first and then gradually add them in little by little. If he doesn't comply, he's not being stubborn or naughty. He's simply undertrained and needs more practice. He hasn't had a strong enough history of reinforcement for the behavior. If you give a command to sit, and he doesn't, simply try again. Help him. Get his attenion, but do it kindly. He's just an animal. And then go home and practice in a boring place for a few weeks, adding a small distraction here and there, building up etc Lots of reinforcing needs to be done in all kinds of contexts and locations and varying degrees of distractions, from differnt positions in relation to where you're standing and where you're facing. It's not as simple to a dog as one might think.
People think their dog knows sit because everytime they ask him to sit, they're standing in front of him, facing him, perhaps looking at him with one hand held behind their back. Then they tell him to sit, but their hand isn't behind their back and they're looking sideways. To the dog, this may not necessarily mean to sit. Dogs watch our body language to the extreme and it becomes part of the cue. If the owner changes the cue when the dog has not had enough practice, and the dog doesn't comply, the owner calls him "stubborn" and punishes him.
Once the dog gets profficient at sitting with variations in location and contexts, you still have your work cut out for you....standing in different positions, sitting down one time, standing with your back to your dog 25 feet away, telling him to sit when you're inside, leaning out the window and hes in the yard. Will he still sit? If he doesn't, he does not know "sit" thoroughly.
Dogs don't generalize well. All these positions and locations have the potential to mean something different than sit.
So, your dog will be much less likely to fail or "blow you off" if you set him up to succeed by not placing him in an impossible environment for the level of training he's in. If you ask too much of him too soon....he's not ready for that, he will fail. It's not his fault. It's the trainers for expecting him to pay attention when he just can't or he simply doesn't know what you mean. If he fails, go back to a stage where he was successful and work more there. He MUST succeed at baby steps....lower levels before he can succeed in more difficult levels. You don't scold a baby for not being able to walk when he hasn't learned to crawl yet, right? You don't accuse the dog of being stubborn and insubordinate if he fails to comply when he's undertrained.