I don't want to sound facetious, but humour is the key to the soul. You know what I mean?
Our writers are full of cliches just as old barns are full of bats. There is obviously no rule about this, except that anything that you suspect of being a cliche undoubtedly is one and had better be removed.
Postmodernism surely requires an even greater grasp of symbolism, as it's increasingly an art of gesture alone.

