Perhaps The Earliest Example Of,

'if you take a commission, do not upset the client!'

 when John Milton’s publisher insisted that he include a portrait in his first collection of poetry, Poems of Mr. John Milton (1645), he called on the services of the prolific engraver William Marshall, Milton was thirty-seven and had that year begun losing his sight, He would however not be blind for another seven years and could see well enough that the resulting frontispiece was appalling, comparison with other Milton portraits suggests that Marshall supplied the poet and polemicist with an overly large nose, extra greasy hair and puckered lips, so what to do? how could Milton publicly deride the engraver?

 this is how he did it, knowing that Marshall did not understand Greek, but many of his readers did, underneath the frontispiece he had Marshall painstakingly engrave a scathing appraisal of it in a language he clearly could not understand, Greek, this is the translation:

Looking at the form of the original, you could say, perhaps, that this likeness had been drawn by a rank beginner; but, my friends, since you do not recognise what is pictured here, have a chuckle at a caricature by a good-for-nothing artist.

although Marshall did not know Greek, he likely could make at least some sense of Latin, which makes another aspect of the portrait surprising, surrounding its oval border is a Latin description, “John Milton, Englishman pictured at age twenty-one.” Yet the face peering out looks much nearer forty than twenty, you must remember that the 'in joke appraisal' would soon spread to those purchasers who could not understand Greek, which begs the question, when Marshall found out what he had done, did he sue Milton?