What makes you trust someone in a professional context? I liked this simple equation by Charles Green which makes it a combination of how credible, reliable, and how intimate — or how safe you feel with that person — divided by the self-orientation of the person — are they focused on their interests, or simply paying more attention to themselves vs being genuinely interested in you and your success. Depending on how you scored this abstract model I guess that would mean that trust is either undermined by someone focusing on their own interests, or strengthened the more they are focused on yours.
More at Trusted Advisor.
Also see: the most beautiful equation.
HT: Buzz Pearce