interesting question. I believe we all have been guilty of ‘beautifying the facts’. As in “have you exercised as regularly as you promised”.
As Nancy mentioned, when we first meet clients, we are strangers to each other, and yet the discussion about client issues can get very personal. I often find that I get omissions rather than lies. Some important pieces of information that I may get later, sometimes hear from a spouse. It often happens when the client considers it embarrassing. And it is sometimes not even intentional but truly a Freudian slip.