Among those of us who semi-regularly celebrate the Common Man and that same fellow's uncommon sense, there is now loose a virulent strain of pernicious snobbishness.

One unmistakable symptom is the infected's compulsion, all the time sneering, to refer to a well-known public figure's earlier jobs or occupations, as in ex-haberdasher. That was big during the administration of Harry Truman. In 1922, some 26 years before he ran for president, Truman's clothing store went broke. Thus, his critics could later ask each other: "Really, what could you expect from a failed ex-haberdasher?"

During the Nixon administration, not a week passed without some sage reminding readers that the then presidential press secretary Ron Ziegler had once worked as a guide at Disneyland. (Ha Ha.) Too bad Ron couldn't have afforded to spend the summer at a good tennis camp instead.

The "ex-" is always important to convey the full flavor of intended disparagement. "Former" is much too respectful and reserved for use with persons like past presidents of Yale.

"Ex-" on the other hand, is used with convicts, alcoholics and addicts, as well as to identify the previous occupations of present officeholders of whom the speaker does not approve.

What was a cheap shot in 1951 on Harry Truman remains a cheap shot in 1981 on Ronald Reagan. It seems to have escaped some people that since he made movies, Ronald Reagan has twice been elected governor of our most populous and arguably most complex state and has once been elected president. Still, some persist in referring to him as an ex-movie star and in writing of how difficult it is for Europeans to grasp our electing an ex-movie star president.

Presumably, Reagan never qualified for designation as "a film star" or "film actor." Making films is much more respectable than making movies. And if one is truly serious about films, then one confides to Merv or Johnny or Tom Snyder that one's ambition is to "direct" or, better, to do a play.

The ex-actor charge has been used before on Reagan with very little success. In 1966, Reagan's California opponent was incumbent Democratic governor Pat Brown. One of Brown's television commercials included the Democrat asking one black girl in a group of elementary schoolchildren, with a wind: "You know it was an actor who shot president Lincoln, don't you?"

Frequent references are still heard about Reagan's polished public performance. Let us be frank about a couple of things. Very few candidates for any office get up and simply wing a few remarks before any crowd. A presidential candidate's most valuable possession is his basic speech, which he has perfected and burnished over years; most candidates would sooner part with their finance chairman.

But there is absolutely no way that Ronald Reagan could have rehearsed his performance in Nashua last February when his outrage was perfectly commensurate with the actions of an insensitive publisher. It was solid political instinct, totally unchoreographed, which brought Reagan at midnight to the Detroit convention hall to announce his choice of George Bush, and which named Jimmy Carter special envoy to the 52 freed Americans. Politics cannot be scripted in such situations. Either you have it or you don't. There is no time to rewrite the second act. It makes little difference whether you were a haberdasher or a mortgage banker in an earlier life.

But most of all, beyond the sensibilities of the public men involved, there is something really quite unsettling about this inclination to pigeonhole people. It is lazy. And it is also quite anti-Horatio Alger, even un-American in a literal sense. It may still be okay to rise from humble beginnings. But in doing so, you'd better be sure that what you do to pay the rent or the tuition along the way is acceptable to those who keep track of such things.

If the inimitable Herblock could give his longtime adversary Richard Nixon a clean shave as an inaugural present, then certainly the rest of us can kick the habit of referring to the 40th president as an "ex-actor." How about "former governor of California?"