This is a really funny questions, and my guess about its origin is, that it's based on a perception of hypnosis like it's presented in cartoons. When hypnosis is used in cartoons it enables the "hypnotist" to gain total control of the subject. If you think that when hypnosis is "working" that you have total control over an individual, then you are on the right track asking that question, because NO it doesn't work that way.

Another aspect could be stage hypnotists (if you have read other answers, you will know by now, that stage hypnotists are responsible for many misunderstandings about hypnosis). When you make hypnosis a show, you have to entertain the audience, and one way of doing this is to show some hypnotic phenomena. If you are questioning wether these are actually true, the answer is yes. By using hypnosis your mind can indeed make potatoes taste like apples and your mind is also capable of letting you experience that you cannot control your body with your consciousness.

So the phenomena are real, but it's important that you understand, that they are not forced into the subject by the hypnotist. What the hypnotist does is merely make a suggestion that the unconscious mind is free to act upon. Wether or not the unconscious mind will act upon the suggestion will depend on many factors including the beliefs and values of the subject. At times it may look like the hypnotist is in control, but the real control is within the subject.

There is also the question if hypnosis works for a particular problem, and there are many anecdotes about the effect of hypnosis. It's however very different if hypnosis will be effectful after just one treatment, or if several are needed, and the succes greatly depends on the hypnotist. It's not evidence that hypnosis doesn't work for a particular problem, if you only try one treatment at one hypnotist!