"I shall also be bold to affirm, that among the ancients, there was not much delicacy of breeding, or that polite deference and respect, which civility obliges us either to express or counterfeit towards the persons with whom we converse." (Hume, "Of the Rise and Progress of the Arts of Sciences").
Not unlike Mohan ("Politeness is appearing to respect another"), Hume (a keen observer of the "old-fashioned English") connects politeness to respect or at least the appearance of respect in his essay (which is a kind of geneology of politeness). [See here for a great paper on the contexts of Hume's views on politeness.] Moreover, Hume is clear that politeness is a consequence of good breeding. With early modern authors it is never easy to tell whether such breeding is merely a matter of good education and proper institutions or if it implies some eugenic features, but that need not concern us here. (It is not simple, because Hume connects the right sort of politeness to gallantry, and he thinks that is a "natural passion.") Unlike Mohan (who is silent on the matter), Hume recognizes different kinds of politeness and he rates the Modern version an improvement over the Ancient one (which -- like my fellow Dutch -- is too blunt in its expressions of respect; Hume quotes Rousseau on the mater: ""The republics in EUROPE are at present noted for want of politeness. The good-manners of a SWISS civilized in HOLLAND," is an expression for rusticity among the FRENCH."). (One gets the sense that Mohan recognizes differences in etiquette, but thinks politeness is uniform.) Now crucially, according to Hume the Modern version of politeness has been shaped by norms of civility, that is, it has been influenced by a courtly culture, which is why "a civilized monarchy" is most favorable "to that of the polite arts."
Well, when we reflect on courtly culture, we immediate realize that there respect is accorded to rank or to being a courtier. This is why Hume so commonly associates politeness to deference. So, polite respect is not due to some intrinsic human worth. Now, politeness can spread beyond the court. According to Hume this is due to emulation. It is quite possible, of course, that during the spread politeness becomes disassociated from deference. Let's stipulate this is true of the version endorsed by Mohan. Even so, it is, thus, eminently possible that a particular system of politeness, which is, say, based on a convention of systematic inclusion of privileged insiders and exclusion of some (or many) outsiders, is -- however beautiful and gratifying -- immoral by our lights. (In his piece, Mohan had recognized the "polite scoundrel," after all.) Hume, for example, suggests there is no "better school for manners, than the company of virtuous women;" and he does so in the context where the virtue of a woman ("softness and modesty") is entirely one appropriate to disenfranchisement (even thought is a is a public virtue--in context, Hume is criticizing the Ancients for keeping women locked inside their homes).