Although the Carpenters were once derided by critics for their tuneful-but- funkless songs, this hit-happy collection of '70s chart-toppers provides ample proof that the duo's work was more pop than corn. Their secret? Richard Carpenter recognized the value of top songwriters and industrial-strength melodies. He also took care to highlight the squeaky-clean vocals of his sister, Karen, using dramatic arrangements to sharpen the hooks on low-key lounge classics, ( Bacharach-David's "Close To You," ) and to beef up the choruses on more upbeat numbers. Viewed with 20/20 hindsight, some of the late Ms. Carpenter's songs now seem more poignant than when she recorded them - - especially "Superstar," with its tale of spurned love, and "Hurting Each Other." Thanks to arrangements that bounce like a Superball, the sunny "Top of the World" and "Sing" still sound fresh; their charming sing-along melodies boost lyrics that might have sounded trite in the hands of lesser talent.