Gossip about diplomatic receptions, henpecked ambassadors, interpretations of a general's smiles or an official's "twinkling eye" were among the classified secrets that helped convict two men of esplonage charges last week.

The diplomatic cables, introduced under seal during the trial of former U.S. Information Agency employe Ronald L. Humphrey and Vietnamese expatriate David Truong, were made public this week.

While the cables do contain some serious diplomatic assessments, such as an American Embassy's view of anticommunist resistance in Laos, the classified cables, for the most part, deal with less serious matters. In total, they present a picture of American embassy officials grasping at press reports, minute social nuances, refugee accounts, rumors and conversations with foreign embassy officials in order to understand what was happening in Southeast Asia in the spring of 1977.

But the cables do not, on their face, resolve questions raised by lawyers for Truong and Humphrey about whether their release would jeopardize the "national defense," and therefore, warrant the conviction of Humphrey and Troung on charges of espionage. Each man could face a life sentence in prison, but sentencing dates have yet to be set.

Officials at the State Department insisted yesterday that in combination with other bits and pieces of information, and because the cables named so many confidential sources, the cables could bring serious damage to U.S. foreign policy goals. They could conceivably endanger the lives of some individuals, some officials said. At the least, the cables are "highly embarrassing," they said.

A February 1977 confidential air-gram from the U.S. Embassy in Bangkok reported that an unnamed Swiss representative of an international organization believed that Gen. Giap, a key Vietnamese strategist, "has a 'fantastic' sense of humor," and passed "humorous notes" back and forth during a meeting of the National Assembly.

A confidential cable from the U.S. Embassy in Laos drew a portrait of the Fannish ambassador to Hanoi as constantly "submitting quietly" to his wife's "corrections and amplifications" when he was speaking to U.S. officials.

An airgram classified as confidential from the U.S. Embassy in Bangkok said the Russians "cuddled the Vietnamese a great deal" at a reception there.

Other cables contain more serious information, though often from sources of dubious reliability.

A lengthy analysis of Laotian resistance efforts against the Vietnamese-backed Laotian People's Democratic Republic, sent from Bangkok in March 1977 and classified "confidential," is based on information that "at best . . .must be regarded as tentative and largely unconfirmed," said the cable.

State Department officials point out that the analysis contained in the document is its most vital element, and would have been of considerable interest to the Vietnamese.

One cable from a U.S. consulate in Hong Kong, classified secret and marked for limited distribution, concluded that there is "little likelihood that China will alter its basic principles for normalization (of diplomatic relations) as a result of any action the United States might take in Vietnam."

Many of the cables relay in part - and in some cases entirely - on published press reports. One, marked "secret," is effectively a rebuttal to a United Press International story that suggested that there are several American servicemen still alive in Vietnam.

One State Department source said that a list was compiled of more than 30 people who might be jeopardized "in some way" by release of the cables. State Department officials were unable to cite any instances in which the release of the cables has in fact brought such retaliation.

Most of the documents were handed over to the Vietnamese by a Central Intelligence Agency double agent in April 1977.

When the documents were first examined by State Department officials in late April and early May in 1977, according to court testimony, their assessment of the damage done by giving them to Vietnam was "minor." Deputy Assistant Secretary of State for East Asia Robert B. Oakley said, however, it was always thought that the "long-term damage could be considerable."