Lately in my campaing, I've had it become the shtick of a certain NPC, that she tells the PC:s the truth (because they have an Angel with high wisdom and a hair trigger on reading a person) but usually not the whole truth (because she considers manipulating the PC:s the easiest way of getting things done, and telling them the whole truth would likely make them sabotage her plans). And as such, frequently when the she is done giving the PC:s an info dump on whatever she ask of them, or her plans or something else like that, the Angel spends his hold to ask whether she's telling the truth. My answer is always the same: "All she has told you is true, so if she is lying, she is lying by omission."
I have begun to wonder, is this telling what honesty demands. Or to be precise, am I using the wording and not telling whether she's lying by omission as a way to obscure her intentions and the developments in the world?
Then again, implying that she may have been lying by omission has made the PC:s really suspicious regarding her (not lessened by asking what she intends to do next giving some pretty incriminating results) and as such, theorizing (usually correctly) what she has omitted.