I go by the ultimate source of all knowledge, the Rock of Ages, otherwise known as the Holy Bible.
God says that we are to be in control of our OWN minds. Hypnotism gives someone else control and allows an opportunity for unknown spirits to toy around as well.
That's also why meditation is a no-no. That is this silly eastern meditation where one is supposed to EMPTY one's mind. Biblical meditation involves FILLING one's mind with sound Biblical thoughts.
To the Christian, idle words and idle thoughts are sin. Hypnotism and eastern meditation are both forms of idleness.
And that's also why fasting is such a wonderful tool as it not only benefits our physical well-being but also our mental and spiritual health as well if properly applied. How many times do we hear that after a fast one's mental clarity is enhanced?
To judge if something is occultic, one needs authority to do so. That authority is the Bible. The occult can often be very subtle (Genesis 3:1). It is not only about human sacrifice and drinking blood. It also incorporates such "innocent" things as Harry Potter and the Chronicles of Narnia.