I remember many years ago, going through a particularly difficult dismissal and subsequent tribunal claim where the person in question had lied about things I found hard to stomach. Afterwards I commented to a (much wiser) trustee that I would never again trust anything said to me if I'd not checked it myself.

She said no - that if you started to believe that everyone will lie to you, then you've lost something of yourself in the process and that you can't do this job any more. Trust in people, because they are mainly good - check what you can where it's reasonable (definitely - that's just sensible practice), but when you find yourself in one of those difficult situations where you despair of the actions a person has taken, remember it's them that is the anomaly and that most people are brilliant. In this job you tend to have more to do with the challenging types, but you need to bear in mind that they are not the norm.