From Wikipedia: abydocomist "A liar who boasts of their falsehood."

Perhaps the most memorable example of this is Anthony's eulogy to Caesar in Shakespeare's "Julius Caesar":

"I come to bury Caesar, not to praise him. The evil that men do lives after them. The good is oft interred with their bones. So let it be with Caesar."

Liars who lie to tell a greater truth are sometimes called poets, Father Steve. :)

We see something similar in GBS' play "Major Barbara" where a lead character says of Undershaft, the owner of the munitions factory, something like this [alas, I can't quote exactly]:

"We can praise him for preaching good and practising evil, but we can't have him preaching evil and doing good." EDIT*: Just found actual quote at the Library. I have reproduced it below in case anyone has an interest.

Here is a review which bears on this Shavian "paradox":

The relativity of morality is illustrated with the paradox of the Salvation Army being described as an ugly nest of hypocrisy, and the armament-factory of “the Prince of Darkness” being described as a happy and prosperous place. That is Shavian paradox at work: what everybody expects to be Hell is as beautiful as Paradise. Undershaft’s welfare town is a small-scale attempt at socialism, and the direct improvement in the life of the employees satiates them, which suits Undershaft.

http://snipurl.com/ddy8

* Speaker was Lady Britomart, Andrew Undershaft's estranged wife, speaking of Undershaft:

"Just as one doesn't mind men practising immorality so long as they own that they are in the wrong by preaching morality; so I couldn't forgive Andrew for preaching immorality while he practised morality." [Act I]