A simple variant with interesting results would be to deal everyone one card from a full deck. Anyone who is dealt a diamond is a deceiver. The dealer can be the spokesman, so it will rotate each turn. This way there is a 1⁄4 chance that any given person is a deceiver, and a small (1/(4^n))-ish chance that all n players (including the dealer) are trying to deceive each other.
Trying to reach the best outcome for everyone with an unknown number of deceivers in the mix? Sounds like life.
Sydney, Australia
But I could make it to Canberra ;)