Hypnosis is open to abuse and it can be performed without consent and without the subject's knowledge. I have been to a talk by two hypnotists where they were at pains to distinguish 'hypnosis' from 'mind control'. The underlying techniques are very similar, and it is largely a question of the context in which the techniques take place.
Modern hypnotist subscribe to an ethics of conduct where hypnosis is performed with full and informed consent of the subject. However, is this enough? Few hypnotists are fully aware of the damage that can be caused by hypnosis used with carelessness. Many are also not aware of the ease with which hypnosis can be misused.The problem is compounded by the fact that certain people with a deep need to have power over others will be drawn to hypnosis as a profession.
To-Do: I include (with permission) a first hand account of abusive hypnosis where from the subject's viewpoint the hypnotist was more interested in power over the subject than in using hypnosis to help.
I intend to add a FAQ about hypnosis here in due course. If you want to see it sooner or would like to help in creating it, do send an email to me (see main page for how to contact).