YOU CAN SAY what you will about Ralph Nader, an American of Lebanese descent - and we have done so ourselves from time to time without an extravagance of affection. But there is one thing he is not: a dirtyarab. We have run the words together because that it the way they seem to have been expressed by Federal Trade Commissioner Paul rand Dixon in some public remarks that recently came to light. In ethic epithet-ese the dismissive adjective ("little," "dirty") is almost always affixed to the noun, like a bur is affixed to a donkey's backside. John J. Wilson, when he was H. R. Haldeman's and John Ehrlichman's lawyer a few years back, for instance, characterized Senator Daniel Inouye as a "littlejap" - or at least that's the way it sound to us.

Speaking of donkey's backsides, you have to ask yourself how Mr. Dixon could have to ask yourself how Mr. Dixon could have been imprudent enough to make his remark - never mind its crudity - given the range of our recent and sorry national experience in these matters, fron General Brown's Jewish bankers to Earl Butz's loose shoes. The answer seems to be that Mr. Dixon is not very perceptive or sensitive to put it mildly; and if you have any doubts about that you need only consider his quasi-apology when a reporter first asked him about the original remark: "If I said anything like that it a mistake. There may be a hell of a lot good Arabs who might (take offense). . . " In an excess of magnanimity, he elaborated: "I understand there are Arabs who are not sdirty."

Imagine - there may actually be "a hell of a lot of good Arab". . . somewhere. . .and not all Arabs are dirty. How's that for a concession? Do you suppose some of Mr. Dixon's "best friends" may even be good. clean Arabs? Well, there is really no poiny sporting far as to benighted Mr. Dixon, who has now gone so far as to opogise to all Arab-Americans - who are not Ralph Nader. We will leave it to others to explain to him that a) Ralph Nader is an American and b) Arabs as a group are no better andno worse than, let us say, FTC commissioners.

Our parting observation is only this: Mr. Dixon also called Mr. Nader a "son of a bitch," a designation Mr, Nader evidently earned by his relentless pursuit of the inadequacies of the agency for which Mr Dixon works. That Mr. Dixon had to lapse into ethnic and general invective to make this case against Mr. Nader suggests to us anyway that his case wasn't so good to begins with.