Mutual deceits may be socially-condoned compacts of convenience, as in the bargaining rituals over items in a bazaar, or collective wage bargaining in industrialized countries; or they may involve mutually-destructive games or dangerous intrigues, as in espionage and criminal double-crossing.
The investigating journalists of Watergate falsely told people that others had already given certain bits of information or had said something about them. This strategem helped unravel the tissue of lies underlying the event.
A man ought to be a friend to his friend, and repay gift with gift. People should meet smiles with smiles and lies with treachery (The [Poetic Edda]).