I am today enormously proud of my service in the White House and very grateful to Richard Nixon for making it possible.

H.R. Haldeman, in "The Ends of Power"

SURE, BOB. Who wouldn't be enormously proud of, and grateful for, the opportunity to have wallowed in the squalor of the White House that is described in Mr. Haldeman's book about his life and times with Richard Nixon. Never mind that the former president (by Mr. Haldeman's account) was regularly given to lying disarmingly to his most intimate advisers and closest friends, to wild rages and recklessly irresponsible commands, some of which he couldn't even rightly remember; that he was a deep believer in illegal wiretaps and burglaries; that he was, in short, an almost compulsive felon. Who wouldn't have enjoyed working closely with fun-loving John Ehrlichman, who (according to Mr. Haldeman) was given to calling the president the "Mad Monk" and to spending "hours" on a "long-time" project of sending Henry Kissinger official-looking envelopes stuffed with nude pictures of "various starlets Henry had dated," complete with forged presidential memos containing "bizarre demands for certain types of action." And who, for Heaven's sake, would not want jovial, felonious Chuck Colson for a colleague - the president's "hit man" who "encouraged the dark impulses in Nixon's mind, and acted on those impulses instead of ignoring them."

There is much, much more in this sordid chronicle, and we can't deny that it has a certain fascination - an appeal, that is to say, to morbid curiosity of the sort that impels a passerby to strain for a closer look at the carnage of a very bad auto accident. Some of the material is new, in the sense that Mr. Haldeman is saying things that he had never said before and offering genuinely grisly inside glimpses of the Nixon team that had not been previously reported. And some of it, particularly those sections dealing with foreign policy, even has a ring of authenticity. But such is Mr. Haldeman's record for sustained falsehood - for lying systematically and repeatedly under oath about the very matters on which he now professes to be speaking the truth - that his account of events cries out for some literary equivalent of a Surgeon General's warning. It is not a volume to be left within the reach of small children or the impressionable. It's use by even the most careful historians could be dangerous. For Mr. Haldeman is not believable.

It isn't that he may not, at times, be speaking truthfully. Here and there along the way, he may be. The point is that there's no way of telling. By his own publisher's account, he had originally intended to write a book about Mr. Nixon's positive achievements in office, while continuing to "stonewall" Watergate. Then he tuned into Mr. Nixon and David Frost and the book became his answer to the lies he thought his former chief had told about him. It is long on intriguing supposition, theory and speculation, and way short on persuasive evidence or hard facts. Even its most titillating passage, which has to do with what may have been on the infamous 18 1/2-minute gap in the Nixon tapes, is so carefully hedged, as a "reconstruction" of the way the conversation "might" have gone, that it is valueless as hard evidence. And with good reason: Under oath, Mr. Haldeman told quite a different story - he couldn't for the life of him remember what in the world might have been scrubbed from that tape - or what might have scrubbed it. But money, as they say, talks. Now he tells us that he had always believed in a theory, entirely unsubstantiated, that Mr. Nixon did the scrubbing, or tried to, and botched the job. Still later he concluded that maybe Rose Mary Woods did it. Or somebody. "I'm confused," he says, which is another way of saying that, for money, so long as you're not really trying to prove anything, you can say almost any wild and unsubstantiated thing you want.