Decriptive vs Derogatory
Partly it depends on how it is used. Just as EGarrett01 uses the terms “liberal” and “libertarian”in the o.p., he does so as a descriptive term to refer to a particular belief system or outlook. That is not being used as name-calling.
If Egarrett01 were to go around instead using liberal in the manner of “You’re just a stupid liberal,” or "you might as well be a liberal," or “you libertarians." Those would be derogatory name-calling. It depends on the use.
Likewise, it is the same for the metaphorical descriptive term “sheeple.” It can be used for name calling, like if someone goes around simply saying “You’re just a stupid sheeple.” That of course is just as immature as the above examples. However, it can also be used as a descriptive metaphor to refer to a specific outlook. It refers to a mentality of individuals who actively choose to remain ignorant, willfully refusing to consider any information, or ideas that may conflict with the dominant conventional media portrayals. The individual folks who don’t want to learn anything about history, circumstances, reasoning that is not proffered on FOX or MSNBC. In other words individuals who effectively choose to be led by a FOX or MSNBC or political party “shepherd” rather than learning and thinking for themselves.
Many of us were sheeple at one time, willfully refusing to consider or learn anything outside that provided to us by our mainstream media or political leader “shepherds.” It is a natural tendency to try to avoid any cognitive dissonance — anything that conflicts with our preconceived notions of what he “know” or have been taught to believe. We awoke. The sheeple are waking. Help wake others.
So I agree with Egarrett01 that using the term simply for derogatory name-calling is not effective. However, like “liberal” and “libertarian,” is has it useful place as an appropriate descriptive metaphor for a mentality of choosing willful ignorance.
Some examples of effective metaphorical use of “sheep/sheeple”:
Judge Andrew Napolitano’s book A Nation of Sheep
They would be the shepherds over us, their sheep. Certainly such an arrangement presupposes that they are naturally superior to the rest of us. And certainly we are fully justified in demanding from the legislators and organizers proof of this natural superiority. – Frederic Bastiat
I do encourage you to question authority, apply logic, and think for yourself. Look at the forest, not the trees. And the centuries, not the months. Or you might risk being lead willingly, as a sheep, to the slaughter. - Rick Garber, Selfishness vs. “Selfishness".
A society of sheep must in time beget a government of wolves. – Juvenal
Although we give lip service to the notion of freedom, we know that government is no longer the servant of the people but, at last, has become the people's master. We have stood by like timid sheep while the wolf killed—first the weak, then the strays, then those on the outer edges of the flock, until at last the entire flock belonged to the wolf. – Gerry Spence, From Freedom to Slavery
If the freedom of speech is taken away then dumb and silent we may be led, like sheep to the slaughter. – George Washington
No people ever recognize their dictator in advance. He never stands for election on the platform of dictatorship. He always represents himself as the instrument [of] the Incorporated National Will. ... When our dictator turns up you can depend on it that he will be one of the boys, and he will stand for everything traditionally American. And nobody will ever say “Heil” to him, nor will they call him “Fuhrer” or “Duce”. But they will greet him with one great big, universal, democratic, sheeplike bleat of “O.K., Chief! Fix it like you wanna, Chief! Oh Kaaaay!” - Dorothy Thompson, 1935
Absolute power corrupts even when exercised for humane purposes. The benevolent despot who sees himself as a shepherd of the people still demands from others the submissiveness of sheep. – Eric Hoffer
Let it not be said that we did nothing.-Ron Paul
Stand up for what you believe in, even if you stand alone.-Sophia Magdalena Scholl