In my opinion, knowledge of them, and experience as both a client and a professional, therapists lie and manipulate all the time. It is their job. It is what they are trained to do. They rarely admit it and when they do they blame the client or say it is because the therapist was acting for the client's behalf. They are tools to use and that is all. Trusting them for more than they are is not a good idea.
Problems arise when clients think therapists are other than that.