The book, "Emotional Vampires: Dealing with People Who Drain you Dry" has some very helpful information on how to recognize when a narcissist (or other disordered character) is hypnotizing you. You look for the signs in your own reactions:
"Make sure you recognize the warning signs of hypnosis: instant rapport, deviating from standard procedure, thinking in superlatives, discounting objective information, and confusion." Emotional Vampires, pg. 48
These are all signs you look for in yourself.
Here is a summary, mostly in my own words, of each of these warning signs. See the book for more details:
Instant rapport -- That wonderful feeling that you are instantly "clicking" with someone you've just met is a clear warning sign. You have likely stumbled into someone who has either done their research before "accidentally" meeting you or before a job interview, or they are quick to assess what it is you think about yourself and are careful to reflect back to you what you want to hear.
Deviating from standard procedure -- Suddenly you find yourself making exceptions and doing things very differently than you normally do for someone you don't know well.
Thinking in superlatives -- You've just met the most wonderful, most incredible, most charming and thoughtful person ever. Big red sign that someone is messing around inside your head. The author says, "distorted perceptions usually involve superlatives". He also points out that the superlatives can be negative too.
Discounting objective information -- You've been swept off your feet in no time flat. You're loving how you feel around this person -- so much so that you are now avoiding objective sources of information about this person. Or, if you do hear things you don't want to hear, you tell yourself it is somehow different for you. He's different with you. He was different back then. When you find yourself avoiding getting objective information about this person you have a clear sign in yourself that you're very happy in this little fantasy that's been created for you and don't want the bubble popped. You're in trouble if you keep this up. Remember, this doesn't just apply to romantic partners. It can happen with a fellow church or club member, a co-worker, boss, employee, etc.
Confusion -- "Hazy understanding of the reasons for your own reactions, coupled with unusual certainty, is a pretty clear sign that somebody has been messing with your mind." pg. 29
If you find any of these signs in yourself, most particularly when dealing with someone you don't know very well, it is imperative that you stop whatever you're doing and analyze the situation. Don't be afraid to ask yourself why you are reacting the way you are. Be honest with yourself. Don't discount your answers.
Some additional observations about someone who makes you feel confused. Don't assume you're an idiot. See it as a warning sign and stop to figure out what is really happening. I have learned that when someone is making me feel confused and pressured at the same time then I know that I must put them off. "I'll call you with my answer tomorrow." If they say that it'll be too late tomorrow then I now know my answer must be a firm "no thanks". When someone is trying to baffle you with bull-shit and then, in your confused state, try to force you to come up with an immediate response you are dealing with a high-pressure salesman or an emotional vampire.