When does the use of rhetoric cross the line?

Perhaps in a mass democracy the use of rhetoric to generate results is unavoidable, but if the use of the associations of a word, instead of its proper meaning, destroys clarity of discourse and good deliberation, it not only maintains the "citizens" in a juvenile state, but can promote it so that they can be manipulated. The reinforcement of bad mental habits is detrimental to the health of the community.

There is a place for rhetoric in political deliberation, as Aristotle points out, and it is a necessary art for the statesman. Rhetoric, like any art, can be used for good or ill, and we should not be surprised if it is employed in order to maintain political power. (In the Gorgias and Phaedrus, Plato too seems to admit that there is a difference between bad rhetoric, as practiced by people such as the sophists, and good rhetoric, which is employed by philosophers. Plato does not condemn outright all rhetoric as being false and unworthy of the philosopher.)

Still, the current misuse of rhetoric is alarming and yet not unexpected. It is a consequence of the centralization of political power and the dominance of the National Government, and serves an indication that the form of government is not really proportioned to the size of the country. Moreover, it is often used when liberals attack traditionalists and traditional mores to discredit them. We can see examples of this in the enforcement of PCness, or the discrediting of the foes of modern liberal Western democracy. (Related to this is the constant appeal to rights and freedom, without any questioning of what these terms mean and how they are related to the good life.)

Judging from blogs alone there is an increased polarization so that rational discourse between the two sides is no longer possible. From my own personal experience, controversy is avoided among friends who do not share the same beliefs and worldview -- do those who have a different sort of relationship, work colleagues for example, manage to share differences in opinion on certain topics and remain civil? (For example, health care reform.) Probably, since they need to continue working together. But the same may not be true regarding matters relating to PC orthodoxy feminism, race, homosexuality. If the split "spills over" into the real world, and if both sides are able to preserve their beliefs (rather than one side's children being converted by the other), then what will the result, other than fragmentation (peaceful or violent)? The use of rhetoric to stigmatize the opposition and exile it from political discourse, and the adoption of these sound bytes by the masses, can only serve to further the divide.

I should see what Aristotle says about using emotionally-colored words. Are there any fallacies related to the substitution of a word's associations for its proper meaning? (Using the terminology of modern logic, we are talking about the difference between intension and extension, and to use the terms of semiotics, denotation versus connotation.)