I truly believe that there are no such group of people called "difficult clients"...if anything they may be individuals with differing perceptions (will be dealt with by charting, channeling, and 2-way communicating of the expectations - expectations management) or individuals who have an interest-conflict (either self- or positional) from a 'territorial turf' point-of-view (dealt with by stakeholder management, charting of stakeholder needs, peeves, major interests, major objections, principle interests & drivers thereof, expectations of primary benefits -- stakeholder analysis charts, force-field analysis to determine the best "approach" into the objectionable areas...) and turning these into "mini business case" like propositions that can be suitably tabled & presented to the "interested & so-called difficult clients" with the primary objective, theme, & message being - not what they stand to "gain" but what they would "lose" out on... head spinning yet?