Michael Bérubé has some considered advice on name-calling. Here’s the second half of his entry; the first half discusses the origin of the once respectable terms moron and idiot.
The other day, as my poor automobile was minding its own business, just humming along down the highway, it was suddenly set upon by a clump of drivers so reckless and inattentive that I referred to two of them (then in the act of cutting each other off in the left lane) as “idiots.” “You know,’ said my co-pilot, “we should probably retire that word one of these days.” She was right, and I admitted as much at the time. “Besides,” I added, “these guys are really assholes.”
After all, dear reader, it’s not as if the English language is hurtin’ for terms of abuse. If you truly believe that someone is acting unwisely or thinking incompetently, you can draw upon thousands of words that speak about performance rather than capacity, which is far more appropriate anyway (as Chris Clarke has eloquently pointed out). That “moron” you revile might just as easily be a jerk, a jerkoff, or a jackass; the “idiot” in the adjacent car or adjacent voting booth might instead be a fool, a wuss, a sap, a chump, a poltroon, a schlemiel, or a patsy. Even as you read these words, thousands of people are just begging to be called scoundrels, prigs, and coxcombs. Why, there’s even an entire Shakespearean Insult Server available online for those of you who want to hurl especially colorful and vivid forms of contempt and contumely upon your adversaries, so there’s really no excuse for failing to take full advantage of the opportunities afforded by this rich and complex language of ours.
If you’re concerned about stigmatizing jackasses, however, on the grounds that you may likening an innocent beast to a hideous human (or, conversely, figuratively dehumanizing one of your fellow men or women), you can always adopt the more politically correct term “jackass-American,” presuming, of course, that the jackass in question is -American.
So next time you’re fed up with someone and you want to call his or her intelligence or judgment into question, remember: you might be better off with insults that speak to the performance of intelligence or judgment rather than to capacity. This isn’t just a matter of politeness; it’s also a matter of proper English usage. Many, many morons and retards have very good judgment about some matters, whereas many, many ostensibly intelligent people make bafflingly, excruciatingly bad decisions. Why? Because some of them are knaves, and others gulls, and still others hoodlums and miscreants. That’s why.
I find that “assclown” covers those who commit a wide variety of offenses.