Of all the East European countries in the Warsaw Pact, one of the smallest, Hungary, is among the most interesting to Western visitors.

It does not have the toughness one senses in Poland, where there are alternate sources of power to the Communist government in form of a huge Catholic population and workers who have overturned governments twice.

It does not have the overwhelming sense of repression that lingers in Czechoslovakia nor the maverick qualities of resistance to Kremlin foreign policy one sees in Romania.

What Hungary has, however, is a degree of cleverness and williness that seems to filter down through much of its national life. So it is a place of interesting ideas, of subtle understandings, like a twinkle in the eye of one who tells a story with two meanings.

It is country that also has perhaps the most well-traveled and well-informed establishment -- government officials, dipolmats, trade and cultural figures, and journalists -- in Eastern Europe. So, when subtleties unfold here, they tend to be either more meaningful or more fun.

For example, on the night of Nov. 6, the eve of the anniversary of the Soviet Bolshevik Revolution, the Hungarian National Ballet put on a special performance here and invited the corps of foreign ambassadors. The first piece was the Russian Ballet "Raymonda" by Glazunov. The second was Hungarian, "Children's Song" by Dohnanyl. The last piece was "The River by Ellinston, better known as Duke, with choreography by Alvin Ailey.

"We always have balanced programs in the ballet," one Hungarian said later with a smile.

FOR SIX nights here recently, many Hungarians were watching the U.S. telvision series "Washington Behind Closed Doors," a thinly veiled portrait of skulduggery in the Richard Nixon administration based on John Ehrlichman's book "The Company."

It seemed an unlikely place to view such a program, and Hungarians say reaction was mixed.

Some people didn't understand it, didn't know who was who, so it passed over a lot of heads and some said it just showed some dirty political things and that was it," one hungarian said.

"But there was also a positive reaction among a lot of people," he continued. "It showed that there are strong laws and institutions in the U.S., and that even a President can't simply demand a file from some places but has to create a force of plumbers to steal it. It proved the strength of American society that they can make such a program about their own past."

As he said is, a friend pointed out that a Hungarian film called "the witness" was playing in one theater in Budapest, without any advertising, and that it was a devastating satire of this country at the height of the Stalin Era. Also showing here, be noted, is a Soviet film called "the mirror" that has not been seen in Moscow.

WHAT DO SOVIET hard-liners and Communist cadres elsewhere in Eastern Europe think of President Carter? The answer one expects to hear is the common one, that the president is viewed as a relatively weak leader, indecisive and thus a little easier to manipulate, strong on SALT and probably a little weak on defense, and that he may be just a one-term president.

That is not the answer one gets in some Budapest circles, however.

Here, some East-West specialists believe Carter may be perceived by hard-line Soviet and other apparatchiks as "the most deadly enemy of the last 10 years." The reason, they say, in Carter's ideology. "It doesn't matter that he gave up the B1 bomber and the neutron bomb unilaterally. What he didn't give up is his ideology. He hit them very early right on their achilles heel, their weakest point, with his plea for human rights."

That, he says, is the most sensitive and explosive topic in the Soviet bloc, the greatest source of potential trouble, and even though carter has been quiet about it in the past year or so, "the cadres will never trust him."

The Soviets according to some Budapest discussions, also may have made a big mistake in writing off Carter politically as a one-term president. This view is supported mostly by an assessment of the Soviet performance during the Cuban brigade episode in Washington.

While many informed Hungarians believe the White House looked foolish and the Soviets had no reason to back down, the episode threatened SALT II in the Senate.

"The Soviets could have thrown Carter a small piece of meat, something conciliatiory to help him. But they didn't, and it makes you wonder why," one said.