they been selling fake olive oil from the time of the ancient Greeks and Romans
http://www.newyorker.com/magazine/2007/08/13/slippery-business This is a cool article on how they do it now and what they tend to substitute it with.
In 1997 and 1998, olive oil was the most adulterated agricultural product in the European Union, prompting the E.U.’s anti-fraud office to establish an olive-oil task force. (“Profits were comparable to cocaine trafficking, with none of the risks,” one investigator told me.) The E.U. also began phasing out subsidies for olive-oil producers and bottlers, in an effort to reduce crime, and after a few years it disbanded the task force. Yet fraud remains a major international problem: olive oil is far more valuable than most other vegetable oils, but it is costly and time-consuming to produce—and surprisingly easy to doctor. Adulteration is especially common in Italy, the world’s leading importer, consumer, and exporter of olive oil. (For the past ten years, Spain has produced more oil than Italy, but much of it is shipped to Italy for packaging and is sold, legally, as Italian oil.) “The vast majority of frauds uncovered in the food-and-beverage sector involve this product,” Colonel Leopoldo Maria De Filippi, the commander for the northern half of Italy of the N.A.S. Carabinieri, an anti-adulteration group run under the auspices of the Ministry of Health, told me.
In Puglia, which produces about forty per cent of Italy’s olives, growers have been in a near-constant state of crisis for more than a decade. “Thousands of olive-oil producers are victims of this ‘drugged’ market,” Antonio Barile, the president of the Puglia chapter of a major farmers’ union, told me, referring to illegal importations of seed oils and cheap olive oil from outside the E.U., which undercut local farmers. Instead of supporting small growers who make distinctive, premium oils, the Italian government has consistently encouraged quan-tity over quality, to the benefit of large companies that sell bulk oil. It has not implemented a national plan for oil production, has employed a byzantine system for distributing agricultural subsidies, and has often failed to enforce Italian laws and E.U. regulations intended to prevent fraud. The government has been so lax in pursuing some oil crimes that it can seem complicit. In 2000, the European Court of Auditors reported that Italy was responsible for eighty-seven per cent of misappropriated E.U. subsidies to olive-oil bottlers in the preceding fifteen years, and that the government had recovered only a fraction of the money.
