Many positive reinforcement trainers (which I do identify as) tell people to “ignore bad behavior”. As with much advice, depending on context, that can be a mistake. Or at least it isn’t the whole story.
And a huge problem is that many people hear this and think “Yeah, right, my 80 lb dog has my screaming child on the floor and is chewing his head and you want me to ignore it? Send in the shock collar trainer!” No, of course you’re not going to ignore that!
Ignoring would also be a mistake when the dog is engaged in a self-reinforcing behavior, for example, chewing your shoe. The dog would actually prefer that you ignore him then, and he certainly won’t stop doing it if you ignore him. This is a case for better management beforehand: put your shoes away, or contain the puppy where he can’t get to illegal stuff. Then if the management fails (and it often does) you go to redirection. Simply remove the shoe from the dog’s mouth and redirect him to a chewtoy. Now he is performing a reinforceable behavior. And no need for punishment.
Often ignoring is suggested for a dog who is jumping up on you. I used to recommend that myself. It can work, but I see two problems with it. One: some dogs are perfectly happy to jump on your back, bite your shirt, or tug on your pants when you turn away to ignore them. Two: since attention is very reinforcing to most dogs, removal of attention can be very aversive, something I prefer to avoid. I think we should also consider that almost always, dogs are jumping up on us to be friendly and say hi. How confusing and stressful it must be for them when we respond with yelling, pushing them off, nasty physical punishments, or even just turning our backs. Imagine doing that to a friendly stranger who approached and offered to shake your hand.
What I prefer to do now is remind the dog to sit before they jump up and reinforce that, and practice many controlled greeting situations — you know, dog training. Or, depending on the dog, I might just kneel down to greet the dog at their own level. In fact, at my house, if I get down on the floor it’s my dogs’ signal that they are allowed to jump on me.
What I do recommend ignoring is demand barking (or demand pawing!). Example: you are eating something and your dog is sitting there barking loudly and rudely at you. Turning your head away or even walking away is something another dog might do, so dogs seem to understand that. Of course, our impulse is to look at the dog or say something to them like “You stop that!” . . . which is giving the dog attention, which is very rewarding to dogs. So in this case, ignoring is the right thing to do. Caveat: don’t ignore “demand barking” if that is how your dog asks to go outside to potty!
The other time I will tell people to ignore something is when they are teaching a new behavior and the dog is offering something else. This is actually how the process of shaping a behavior with clicker training works. I see this happening quite regularly when a dog is first learning to walk nicely on leash. An excitable dog might be jumping and bouncing at your side as you walk along. This might be because you are holding a treat in your hand some place where the dog thinks he might actually be able to jump up and reach it! If you get the treat out of sight and just ignore the bouncing and keep walking (as long as the leash is still loose) the bouncing will stop, and of course as soon as all four feet are on the floor, you reinforce it.
I think dogs get ignored plenty as it is! In general if we think more about setting dogs up to make good choices we can then have more good interactions with them, rather than focusing on doing yukky stuff to them —including ignoring them.