What qualities make an excellent consultant?

Question

What do CEO's, administrators and others in management see as the most essential features of an excellent consultant (beyond basic expertise, that is)?

Answer 1

It is a great quality for a consultant to be able to understand human (customer) psychology so much as to offer them what they expect, beside what they probably need!!

Answer 2

As the best inside tip I can give you for a consultant - If you work on and address what your client thinks is their problem, maybe you'll get the chance to work on what really is the problem. Which is almost always one or two levels of organization higher than the client thinks it is.