How does Twain's use of charged language such as "exceedingly self-satisfied monarch" best advance his viewpoint? It shows the reader that American railway workers are smug and feel superior to the passengers. It provides the readers with an idea of Twain's admiration for the French railroad conductor. It illustrates Twain's feelings about traveling by rail through the French countryside. It reveals Twain's belief that American railroad workers are inferior to those of France.
Read the passage.

excerpt from "France" in The Innocents Abroad by Mark Twain

In France, all is clockwork, all is order. They make no mistakes. Every third man wears a uniform, and whether he be a marshal of the empire or a brakeman, he is ready and perfectly willing to answer all your questions with tireless politeness, ready to tell you which car to take, yea, and ready to go and put you into it to make sure that you shall not go astray. You cannot pass into the waiting room of the depot till you have secured your ticket, and you cannot pass from its only exit till the train is at its threshold to receive you. Once on board, the train will not start till your ticket has been examined—till every passenger’s ticket has been inspected. This is chiefly for your own good. If by any possibility you have managed to take the wrong train, you will be handed over to a polite official who will take you whither you belong and bestow you with many an affable bow. Your ticket will be inspected every now and then along the route, and when it is time to change cars you will know it. You are in the hands of officials who zealously study your welfare and your interest, instead of turning their talents to the invention of new methods of discommoding and snubbing you, as is very often the main employment of that exceedingly self-satisfied monarch, the railroad conductor of America.