Lack of a referential index is a deletion where there’s an unspecified party or an unknown “they.” If someone tells you, “Everybody knows you’re a liar,” you could say, “Who on earth would say something like that about someone like me?” That kind of backs the person into a corner, challenging them to disclose their sources. Maybe someone does think that you’re a liar or that you lied about something, but how could every single person think that? Has this person been telling stories behind your back? At the very least, your meta-model question shows them that you can’t be intimidated by such a cheap shot.