IT'S BEGINNING to look as though there must be a mole somewhere in the Reagan administration's personnel operation. The mole -- if this theory is right -- is planting within the government a succession of people whose strange and unattractive opinions on public questions are calculated to damage and embarrass the White House and offend practically everyone else. As a strategy for undermining the administration's reputation for decency and common sense, you'd have to agree that it's extremely effective.

Earlier this week, it had begun to look as though the mole might have vanished. There had been an unaccustomed lull of fully two weeks since the previous personnel fiasco -- the one over the appointee in the Education Department who had attacked aid to handicapped children on grounds that "each of us is responsible for his life situation." But now it appears that the mole has been at work again.

The new chairman of the Copyright Royalty Tribunal, Marianne Mele Hall, had a hand in a book, "Foundations of Sand," that laments the general decline of American society. Among other targets, it denounces those social theorists who "put blacks on welfare so they can continue their jungle freedoms of leisure time and subsidized procreation." It goes on at some length on the general theme of inherited behavior and the influence of the millennia in the jungle. If you were to read the book, you would find these ideas unpleasantly familiar. Mrs. Hall's name, with others, is on the title page; she once described herself as a co-author, but more recently has explained that her contribution was more in the nature of editing the book. The distinction is not crucial.

The Copyright Royalty Tribunal is an obscure little office, as federal agencies go. But its five commissioners are appointed by the president and are subject to Senate confirmation. Mrs. Hall was confirmed a month ago. She was called back yesterday before a Judiciary subcommittee to explain some points that might better have been raised earlier. But, as one of the senators said, now she's in office for a seven-year term. The mole has scored again.

But maybe there's no mole at all. One other explanation is possible, although it's unappealing. Perhaps this succession of wildly bad appointments simply represents the administration's idea of adequate standards. Perhaps the selection process is in the hands of people who don't think that candidates' views on subjects such as race are relevant to their fitness for federal office. That's possible. If it's true, it is a terrible indictment of the White House.