Sorry to respond so late with this, but I was kind of busy this weekend.
Now, of course, NLP and hypnosis will not work in a bar, if it seems to work, that's only because the person doing it has more confidence in her/him self and that will shine through. Confidence is usually more desirable in a person than no confidence. But, in the end, a "subject" will make the final choice of how to react to NLP or hypnosis.
And that's the point I'm trying to make. For example, my girlfriend drops into a trace when I touch her because she
wants to (I am her boyfriend, I didn't get her to be my girlfriend through hypnosis, I did it the old-fashioned way

) and
expects it to happen. Same thing when I do a show: the audience pays to sit and allow me to manipulate them. They put me in a very powerful position, but, truth be known, they can take that power away by just not wanting the show to go well.
I know NLP has other "tricks" to make people do your bidding, but all those things fall flat if the subject simply doesn't want to do what you are trying to get them to do. Desire and belief go a long way in aiding psychological manipulation.
To go a little further with this whole manipulation thing, it seems to me that basically we all do it. Even the very young. From a child who cries to his parents to buy him a G.I. Joe with the Kung-Fu grip to a person using her/his sexiness to get you to buy this shaver instead of that one, we all do it. Sometimes it works, sometimes not. It might work on some people, it might not on others.
Let me give you another example of this: advertising. How well does it really work? I mean, it's an advertiser's job to get you to buy their product. Their job is to manipulate you to like their product more than any other product in out there. If psychological manipulation, i.e. NLP and hypnosis, work as some people give it credit for, then we'd all own every brand of every product out there.
In fact, all this "manipulation" can really do is influnece. It cannot make you do anything. The truth is, the final decision to have some kind of psychological manipulation to work on you is you. Period. You can choose not to listen, or to jump right in. The final choice, no matter how many tricks that are played on you, is yours.
That being said, there is one trick that seems to lower your ability to remember you have that choice: confusion. By my experience and observation, confusion is the only thing that seems to help psychological manipulation. You confuse someone enough they'll be more open to agreeing with you or following orders, etc. It's not fool proof, and if you use it you have to be on your toes, but it's power comes from the idea of catching someone off guard. Hypnotists and NLP'ers use it a lot. Derren Brown illustrates that in a lot of his work.
I say this because confusion (which includes misdirection) is the main weapon used by magicians and con men.
However, even with that, the final choice, the final descion is always and always will be yours.