From the salty Barry Goldwater--Mr. Conservative and Mr. Provocative--the damns, goddams, hells, ass-kickings and other vernacularisms pour out inoffensively. That's good old Barry, say his senatorial colleagues of straighter lace. The latest exercise in Goldwater sassiness came the other day when the 75-year-old senator, the next chairman of the Senate Armed Services Committee, vented against his chums in the Pentagon.

In interviews in The Washington Post and U.S. News & World Report, Goldwater blustered that he wants changes in the military: "It's the whole goddam Pentagon. I don't think it should take 22,000 people to run the whole hierarchy of the military." Goldwater had advice for Commander-in-Chief Reagan on the MX missile debate: "I don't think he can win it, so why get your ass knocked off?"

The senator is against excessive desk work: "There's too many good military men tied up in the Pentagon who ought to get their asses out and go back in the field." Goldwater also announced that he opposes arms industry rip-offs, procurement waste and the MX.

For this seeming toughness, Goldwater is being praised. Last week, Time magazine called him "a curmudgeon with a conscience." With no reelection in 1986, Time added, Goldwater is "even freer to speak his mind."

Conscience ought to be a word applied sparingly to politicians. The memory of those who have earned the praise, as Philip Hart was rightly called "the conscience of the Senate," is demeaned when it is handed out loosely. Goldwater is undeserving. Crankiness is not conscience.

The senator, who is retiring in two years, is merely the latest in a long run of aging militarists who pipe up at career's end about policies they either supported all along or remained silent about when an opposing word might have made a difference. Parting shots are only a cut above cheap shots. In 1982, it was Adm. Hyman Rickover -- the celebrated gift taker -- who left military service with furious slams against military excesses. We must have peace, cried Rickover, after decades of filling the oceans with missile-laden submarines.

Goldwater's pending clampdown has a superficiality all its own. No courage is needed to attack Pentagon waste. Goldwater was on the Armed Services Committee all the years in which the Pentagon was paying $436 for a $7 hammer and $37 for a 4-cent screw. Why no goddams and hells then?

Goldwater is anything but fearless in opposing the MX at this late hour. Everyone from the Mormons to third-generation Republican ranchers in Wyoming have declared it useless and extravagant. All those years of saluting the MX weren't for real, Goldwater now confesses: "My heart has never been in it." Only his voting record.

If the senator had as much character as his admirers believe he has candor, he might be using this moment to level with the public by expressing his regrets about his blind discipleship to the military. An apology would be in order. It has been Senate and House members like Gold-water whose boosterish Americanism has let the Pentagon practice its fiscal gluttony. What blindness afflicts Goldwater that two records needed to be set -- a record military budget and a record deficit -- before he can say, as he now does, that Reagan should freeze military spending?

Perhaps the proper response to Goldwater's so-called conversion should be the mellow one: Let us be grateful for small favors. But the gratefulness grates when other of Goldwater's militaristic lusts are considered. He unhesitatingly favors using combat troops in Central America "if it appears that the Cuban or Soviet philosophy is beginning to prevail." He says nothing about the lack of economic justice or human rights that has led, and is leading, to revolutions in Central America. Instead, "I think we have to do anything we can."

With Central America a U.S.-domi-nated scene of counterinsurgency warfare, construction of airfields, naval maneuvers and recent war games involving 6,000 troops, the military "anything" that Goldwater dreams about may well come to pass.

For an Air Force reserve general who boasts of having flown the U2, the B1 bomber, the F104, the French Mirage, the German-French A300, the SR72 (at a speed of Mach 3) and 165 different types of aircraft, thinking about future wars is only a part-time absorption. Refighting old ones is also fun. The United States, Goldwater says, "lost the last two wars" -- Korea and Vietnam -- because of civilian interference. Goldwater didn't say who should be goddammed, sent to hell or have their asses kicked because of these defeats. But for the next war, he's for leaving it to the military alone to decide how to Stone Age the enemy.

As chairman of the Armed Services Committee, Goldwater could make a valuable contribution to the demilitarizing of America. It's frighteningly unlikely. Something more than crotchety belaborings of the obvious are needed.