Hypnosis aversion works.

All psychotherapy is aimed at changing behaviour.  Hypnosis aversion is a very powerful technique for changing behaviour.

The basic theory of behaviour change is that people will stop doing things they get punished for but will do things they get rewarded for. This is the basis of behavioural therapy.

However, behaviour can only be changed while it's happening. For example, suppose you have a situation where a child is constantly interrupting adults while they talk. If your response is to remove the child from the room, then the behaviour is no longer happening. Problem solved.

But the child is learning nothing. The child may in fact be learning resentment or hatred towards you, which is not actually what you want. The child may in fact be reinforced by the bad behaviour. There might be things to do outside the room which are just as enjoyable. What the child is not getting is any instruction on how to behave while adults are speaking. You can only change behaviour during the behaviour.

External punishment doesn't work

That is why punishment seldom works. The first response to any kind of unwanted behaviour is to punish the person doing it. If that doesn't work then you punish them some more. If that doesn't work punish harder. However the basic problem with that approach is that the punishment is applied after the behaviour has finished. It is too late then. In the criminal justice system people are often punished long after the crime. The criminal may in fact have forgotten the crime by the time they get to court. It is the time difference between the behaviour and the punishment which is crucial. If your finger broke every time you stole something there would be a lot less theft. If your car refused to start after being illegally parked, illegal parking would soon die out. 
It is the immediate link between the behaviour and the punishment which is critical. And the punishment has to happen at the exact time that the behaviour is happening.
That is the critical difference between hypnosis and behavioural approaches. When a bad habit is treated with Hypnosis Aversion a link is formed in the unconscious mind between the behaviour and a feeling. The feeling is usually disgust or fear or some other negative thing. The critical difference is that as soon as the behaviour starts the unconscious mind brings out that horrible taste or fear or whatever it is immediately. There is no delay. There is no gap between the behaviour and the punishment.

And that is why hypnosis aversion works.