Each of us likely knows someone that has had experience working with a person that never seems to be satisfied with the output or the solution that is offered. There are then tales of frustration when the individual rejecting a proposed solution fails to render any reason why that idea is not acceptable, or furthermore, just flat out refuses to join in on helping to identify a resolution. (One often questions how these individuals are appointed to carry the posts that they have, let alone how co-workers must view working with them.)
So, what is the best way to go about working with individuals of this nature, especially when one is your [paying] customer? Is it possible to deliver a solution of value if the expectations are too unrealistic? Our experiences have taught us that in these types of situations, one must remember to hide frustrations and maintain composure. Try to remain visibly positive (as outward expressions and body language have a tendency to reveal otherwise). If necessary, excuse yourself politely or ask if would be acceptable to return a phone call if working remotely. Above all, though, one must remain courteous and patient.
It is in these moments when responding positively is perhaps the only way to diffuse a situation. Remain in control and solve the actual issue at hand, and turn a critic into a pleased customer.