This is one reason that I think a GTD system should be private. If you start sharing it then you will resist putting sensitive things on it. As an extreme example, you would never want to share the "Fix that expensive mistake I made before anyone notices" project, even if you rename it to something less obviously damning.
As much as you wouldn't want anyone finding out about a mistake, that project and associated actions must be on your lists.
Then you also have to be comfortable adding seemingly trivial projects to your list. "Tidy desk", "Clear out middle drawer". This stuff might be important to the owner of those projects but nobody else wants to know.