The going-home party for Walter Mondale and his wife Joan was not so sad as such affairs often are, since most of the guests expect them back in Washington in a couple of years. On Aug. 20, the Mondales are returning to Minneapolis, where the former vice president will join the law firm of Dorsey & Whitney -- and, it is expected, begin rebuilding his political base for a 1990 run against Republican Sen. Rudy Boschwitz. The Mondales, who spent 23 years in Washington, have not sold their Cleveland Park house.

More than 100 well-wishers came to say farewell at the Dupont Circle home of Mondale's presidential campaign manager Jim Johnson and his wife, campaign press secretary Maxine Isaacs. Among the guests were developer and Mondale fundraiser Nate Landow; former assistant secretary of state Richard Holbrooke and his date, CBS correspondent Diane Sawyer; former Mondale Senate press secretary Ernest Lotito and his wife, Peg Cuthbertson Lotito, a former press secretary to Sen. Alan Cranston; Jimmy Carter's presidential press secretary Jody Powell and his wife Nan; speech writer Ray Calamaro; longtime Mondale aide Mike Berman; NBC White House correspondent Andrea Mitchell; and ABC Capitol Hill correspondent Brit Hume. Among the guests were several Mondale workers now toiling for other presidential candidates, including William Daley for Sen. Joseph Biden, Fred Martin for Sen. Albert Gore and John Sasso for Gov. Michael Dukakis.

Tammy Faye on the Tryst Jessica Hahn may tell the world that she was lured into a sexual tryst with PTL leader Jim Bakker, but Tammy Faye isn't buying it. In an interview with the San Francisco Examiner, Tammy Faye Bakker said, "That girl knew exactly what she was doing when she went down there" to Florida in 1980 for the fateful sexual encounter with Bakker that eventually brought down his career. "Besides," she added, "it {the encounter} only lasted 15 minutes . . . and how I know is that Jimmy was late to a telethon. He looked at his watch."

The Bakkers have been staying in San Francisco with attorney Melvin Belli, planning a strategy to regain control of their religious empire. Tammy Faye says she and her husband will be back in the televangelism business. "We don't have any money," she added, "but we have the support of our PTL partners." Out and About The celebrated Capitol Hill town house where then-presidential hopeful Gary Hart was observed hosting Miami sometimes-model Donna Rice is now unfurnished. Yesterday, National Van Lines showed up to haul away the furniture. Movers wouldn't say where they were taking the household goods, but a neighborhood letter carrier said all the mail has been forwarded to Colorado, where Hart and his wife Lee are living. The Harts bought the town house three years ago for about $300,000, and for a time it was on the market with an asking price of about $350,000. The home is no longer listed, and Hope Price, an assistant to the Harts' real estate representative, has refused to comment on why the house is off the market . . .

Singer Perry Como has made a big thing of his early years as a barber. And on Sunday night, when the 75-year-old entertainer finished his performance at Wolf Trap, he met backstage with a Vienna man whose hair Como had cut more than 50 years ago. Mike Abraham told Como that he had visited the Como barber shop in Cannonsburg, Pa., for a 25-cent haircut in preparation for his upcoming bar mitzvah . . .