A few pages into Tom Mueller’s new book, “Extra Virginity,” there’s a funny moment when an olive oil expert holds up a bottle that’s covered with dubious claims: “100 percent Italian,” “cold-pressed,” “extra virgin.” The man shakes his head and says, perhaps with a hint of Don Rickles in his voice, “Extra virgin? What’s this oil got to do with virginity? This is a whore.”

These are sentences to savor. They underscore this book’s project, which is to demonstrate the brazen fraud in the olive oil industry and to teach readers how to sniff out the good stuff. These are also, sad to say, among this book’s few digestible lines. Earnest and sentimental from start to last, “Extra Virginity” doesn’t have a shrewd or slutty bone in its body. It’s an unintentional master class in how to say waxy and embalming things about fresh food.

Mr. Mueller is an American writer who lives in Italy. And not just anywhere in Italy but, his dust flap reveals, in a description that’s the prose equivalent of Corinthian leather upholstery, “in a medieval stone farmhouse surrounded by olive groves in the Ligurian countryside outside of Genoa.”

“Extra Virginity” grew out of a cogent article titled “Slippery Business” that Mr. Mueller wrote about olive oil in 2007 for The New Yorker, and his book is filled with information mindful eaters will wish to have. In this regard “Extra Virginity” is another reminder of why subpar nonfiction is so much better than subpar fiction. With nonfiction at least you can learn something.