It should not be robot-like in its obedience to the point that it cannot share its personality with the client. For example, if the dog is in a session with a child on the floor reading, it should be okay for the dog to lie its head on the leg of the child. The dog should welcome petting.
You have to like what you are doing. Make sure you are comfortable with what you are asked to do. If not, speak up to protect yourself and the dog.