Mostly bad taste, say the former Paris correspondent of The New York Times and his redoubtable food-historian wife. Readers who remember John Hess' all-too-brief stint as Times food critic will know what to expect: a crusading attack on the culinary abuses of the food industry and the frequent idiocies of the cooking writers. Fannie Farmer, say the Hesses, debased the rich, sophisticated culinary heritage which they charmingly document from dozens of earlier American cookbooks. In her wake came decades of sugared bread and pseudo-scientific cant. Thanks to the food industry and its hired home economists, the taste of children (and adults) is horrendously geared to what appears on the local supermarket shelves, and thanks to agribusiness techniques, the nutritional value of even fresh produce declines year by year. Most writing on nutrition simply muddies the issues, the authors claim, and most ""gourmet"" writing is even more appalling. The pretentious chichi that passes for connoisseurship bears little relation to the French traditions it so noisily invokes. Beard, Child, and especially Claiborne are indicted for throwing around expensive ingredients, not bothering to acknowledge sources, and glibly falsifying the character of classical dishes that depend on absolutely fresh produce and simple, deft handling. Altogether, the Hesses give us enough refreshing good sense and conscience for a lifetime. Their untidily digressive style is less of a joy, however, and their frequent tone of ax-grinding vindictiveness may dismay even people who can't stand Claiborne (the chief target) and most of the tribe. A long-overdue book, marred but not vitiated by some crude rhetorical excesses.