Merriam-Webster defines rhetoric as the art of speaking or writing effectively. Dr. L. Kip Wheeler writes the following about rhetoric:
Rhetoric is the ancient art of argumentation and discourse. When we write or speak to convince others of what we believe, we are "rhetors." When we analyze the way rhetoric works, we are "rhetoricians." The earliest known studies of rhetoric come from the Golden Age, when philosophers of ancient Greece discussed logos, ethos, and pathos. Writers in the Roman Empire adapted and modified the Greek ideas. Across the centuries, medieval civilizations also adapted and modified the theories of rhetoric. Even today, many consider the study of rhetoric a central part of a liberal arts education.
St. Augustine taught rhetoric in Milan. Prior to his conversion, the future bishop of Hippo found the persuasive arguments of Bishop Ambrose commending the Christian faith to be instrumental in his conversion to Christianity. In all of his theological works, Augustine not only paid attention to the substance of the argument he was presenting, but to the style, to the art of persuasion in the making of the argument. Substance or the "what" of the argument is crucial, but so is rhetoric, the "how" of the argument, or to put it less awkwardly, how the argument is made.
Rhetoric is critical in the art of persuasion. We recognize this when we comment on someone who says something that does not come out quite right. "It's not what was said; it's how it was said." When we make such a claim we are criticizing someone's lack of rhetorical skills.
So, it seems to me that we should reserve this wonderful term "rhetoric," as it has been traditionally used, and rescue it from politicians and their loyal pundits who could use a little training in the art of the word they use too often and so shabbily; after all, there aren't too many good synonyms for rhetoric in its classical sense, but there are plenty of words that can replace what it is that politicians and their loyal minions often engage in, and it is not the art of persuasion.
Perhaps the best synonym for those kinds of arguments is "demagoguery."