So we know that the noun "Afghan" is preferred over "Afghani" when it comes to describing the people of Afghanistan, but what's the scoop for using it as an adjective? For example, is saying an "Afghani carpet" incorrect, offensive, both or neither, as opposed to an "Afghan carpet"?
Context: A rather lively debate on Travel.SE about whether using the term "Afghani passport" in a newspaper article is a mark of cluelessness.