I have said things like that, too. But I suppose it is hair-splitting, since lots of things I say during play are "untruths", but don't we all do this? I might tell him he's worthless because I know he wants to hear it and it feels damn good to say, but I don't really actually think that, and he knows it. It works the other way, too: he might say "Yes, Mistress, please more" to lots of things he doesn't really want more of- because he wants to please me, so he says what he knows I want to hear.

I think though that is part of what makes it so good: the playing pretend. Also, what you might like to hear will be different from what someone else wants to hear (trust me, "not deserving" is a line that will get him really turned on, really fast). And that is what I mean by being a good Domme; knowing what to say to your sub that makes the best experience for everyone, not just yourself.

PS- I love hearing things from another sub's point of view, I've been with mine for such a long time, this is fun!