I’ve been meaning to put my musings on the books I read on this site for a while. In most instances it will be in areas where I am not an expert.
First off, the title refers to common thread in a person’s character that evokes the common (aka vulgar), or working class. In this case, it refers to mannerisms in the protagonist’s behavior. It does not, as I was expecting, refer to a habit of exploding into profanity-laced tirades by a character.