A professional hypnotist once told me that it is very difficult to hypnotize "mathematicians" (him meaning: math, physics, and computer science students), because (this was his intepretation) they are too well connected with the reality and will not accept nonsense. But he also said that given enough time and trying different hypnotists, probably everyone can be hypnotized.

This happened at a hypnosis training camp, where this guy had an interesting idea: To teach hypnosis more efficiently, he would hypnotize all the participants and give them hypnotic commands to remember the lessons better. And then he would teach the theory and let us do the exercises, as usual. Also, he said that in order to learn hypnosis it is better to be hypnotized first, because then you know what it feels like to be hypnotized, and that knowledge is very useful when hypnotizing others (you have better intuition on what can and cannot work). -- This strategy seemed to work for many participants, most of which were psychology students. Only two people in the group couldn't be hypnotized: me and one girl, both students of computer science. The only time in my life when I regretted I wasn't more susceptible to hypnosis. So at the end, all I learned was some theory.