It is extremely important to be aware of a client's criteria. Any outcome you attempt to give him will be unsatisfactory if it is not in accord with his own criteria. Furthermore, the client's criteria can be powerful leverage for the therapist. Once you know how to listen, you will recognize that people constantly tell you their criteria without even realizing it. These have to do with the fact that we all speak different languages even though we use the same words.
Therapists often seem successful in changing complex equivalences by sheer force of authority.
Undoubtedly this was in part because my teacher, Cameron Bandler, is one of the great masters of the one-liner in therapy. NLP is above all cognitive. Both the verbal and non-verbal aspects of cognition are the arenas for many interventions. The formal structure of the client's cognition is generally given more attention than the content. From the beginning, NLP has had the idea that changing the way a client talks to himself can result in powerful changes.