Good topic, Steve
The thing that springs to mind for me, though, is that trust isn't a binary thing. So often we'll hear someone being told that they should trust so-and-so. In practice, what should be happening is that the person should be learning in which ways they can trust so-and-so.
I work with someone who, because of their organisational skills, can be trusted to manage a project VERY well. However, there's a significant gap between how advanced they believe their technical skills to be, how advanced everyone else believes them to be and how advanced they actually are. For that reason I don't believe them to be worthy of trust in certain areas.
Some of those areas can be changed by my (and other people) spending time passing on knowledge. Some are beyond that person's comprehension. Net result is that I trust that person implicitly with some things and not with others. That person values the former and respects the latter, ending up with a good working relationship but relatively little exposure.
Basically, I believe it is foolish to trust too little but also foolhardy to trust too much. And you can only find a good balance if you're already inclined towards co-operation, and therefore prepared to put in the effort.
Semper in excretia, sumus solum profundum variat