"The propensity to manufacture propaganda in the Arab world is traditionally accepted as a method to safeguard honor and status and to avoid shame. It is not, as David Pryce-Jones explained in The Closed Circle: An Interpretation of the Arabs, a matter of morality or malice. “If honor so demands, “ he said, “lies and cheating may become absolute imperatives.” In fact, exploiting every possibility for converting shame to honor is considered a noble skill. Shia practice recognizes this predicament and permits taqyia, or “precautionary dissimulation” where Muslims can lie and cheat with religious sanctity.
Robert Spencer covers this in great detail in his "Politically Incorrect Guide to Islam(And the Crusades)". Very well-sourced book and it appears that this is the case.