Pearl writes too much about Dupin, who cares if the detective was rude to his house servants and unfriendly. Who cares that he disregarded a person when they talked. He was a detective after all, a man of observation not a man of social etiquette. I didn't expect to be reading Sherlocke Holmes, but with this novel I may as well have read the whole Sherlocke series with the depth of detective characteristics shown.
The way that the french detective explains his perception of Americans once he arrives in America does not surprise me. He says that Americans are rude, that they are too direct and spit their tobacco juice on the streets: unawares of any passer-by.