I've tried hypnotherapy with this woman who coughed during it and I couldn't relax and get into it. However having tried yoga, I really loved the relaxation bit at the end where you ly down on the floor and the woman speaks softly to get you to relax, which worked a wonder as some people were snoring. Sometimes a person on tv would have a very hypnotic voice for me and my head feels heavy. So i think it's down to who is hypnotising you, the perfect voice and mannerism is key, and of course that can be different for everyone.
I had some Paul Mckenna hypnotic CDs on self confidence. I listened to them at night and I'd wake up hearing him say, wake up, wake up, so maybe he did hypnotise me, but I saw no change in my thinking or behaviour.