This episode's headline: HUD Scandal; Watermelons - Seeds of Success; Cholesterol Controversy. The guests include REP. TOM LANTOS, [D] California; REP. CHRISTOPHER SHAYS, [R] Connecticut; DR. ROBERT OLSON, State University of N.Y., Stony Brook; DR. DEWITT GOODMAN, Columbia University; CORRESPONDENTS: KWAME HOLMAN; PAUL SOLMAN. Byline: In Washington: JAMES LEHRER; In New York: CHARLAYNE HUNTER- GAULT