Cases before the House ethics committee are stacking up like planes at Washington’s National Airport, and so are the embarrassments for Congress. After the committee investigates Georgia Republican Newt Gingrich for a questionable book deal, it must consider Ohio Republican Donald Lukens, convicted in May of having sex with a 16-year-old girl. Then it will weigh the case of Illinois Democrat Gus Savage, accused of fondling an unwilling Peace Corps volunteer during a March trip to Zaire. Last week the committee agreed to investigate Massachusetts Democrat Barney Frank, who has admitted that he had an affair with a male prostitute. On a scale of 1 to HUD, Frank’s transgression is a low single digit: there is no suggestion that he used his public office for personal gain. In the eyes of some, however, private failings are far more serious: they go to a leader’s judgment and character, as Gary Hart and John Tower learned. For many people, the fact that the scandal involves gay sex makes Frank’s behavior more offensive; among others, tolerance of homosexuality has shielded Frank from sharper criticism. At the least, Frank’s judgment was appallingly naive. After an initial encounter in which he paid Steve Gobie $80 for sex, the Congressman says he tried to lift the younger man out of drugs and prostitution by hiring him to run errands. He wrote letters to Gobie’s probation officer and paid his psychiatric bills. He allowed Gobie the use of a car and sometimes his apartment when he was out of town. After 18 months, Frank says, he dismissed Gobie upon discovering that he was bringing clients to Frank’s apartment. Two years later, Gobie tried unsuccessfully to sell his story to the Washington Post. He then gave the story to the Washington Times for nothing, in hopes of getting a book contract for the male version of The Mayflower Madam. This week Gobie will appear on Geraldo, discussing his prospects for a television mini-series. While the House could censure Frank or reprimand him, colleagues and constituents so far have been generally sympathetic. The scandal does not involve seducing a minor, as it does with Lukens, or adultery, since Frank is single. It is an incident from a past secret life that has come back to haunt a legislator who is widely respected. Frank can debate and speak extemporaneously better than almost anyone else in the House, and he tackles some of its more complex problems like immigration and housing. Back home, he makes sure constituents get help from 18 staffers who track down Social Security checks and Medicaid benefits. Though he freely disclosed in 1987 that he was a homosexual, his district, which encompasses the liberal campuses of Boston and nearby blue-collar mill towns, re-elected him overwhelmingly in 1988 with 70% of the vote. Massachusetts Republicans have jumped on the Frank affair, and the latest poll shows that only 45% of the Congressman’s constituents still look on him favorably — a blow but not necessarily a defeat, since 61% want him to run for office again next year. Alexander Tennant, Massachusetts G.O.P. state committee director, says the political issue is “not Barney Frank’s sex life but whether the Congressman broke the law.” Gobie says he did, by abusing congressional immunity to avoid paying Gobie’s parking tickets, a charge Frank denies.