I just finished reading
Extra Virginity, a book about the Olive Oil business, primarily olive oil fraud. Lately this has become part of the internet rumor mill again, with references to the 2010 UC Davis report. Here's some takeaways from the book (which you should totally read) on fake olive oil:
1. Extra Virgin olive oil is fake in any of 4 ways, from the most to the least common:
a. labelled as Italian or Greek but grown somewhere else
b. real olive oil, but low-quality "deodorized" pomace or "lampante*" oil
c. olive oil adulterated with nut or seed oils
d. not olive oil at all, really canola oil with food coloring and flavorings
2. The majority of Italian Extra Virgin olive oil sold (in the US or anywhere else) is fake in at least one of those four ways, including premium brands.
3. You're more likely to get the authentic article if you buy California or Australian EV, because those two countries have more stringent standards than the EU (yes, really).
4. If you're buying EV for less than $15/liter, it's almost certainly adulterated**.
More info on the author's website:
http://www.truthinoliveoil.com/(* "lampante" == "suitable only for burning in a lamp". Based on the grading of olive oils invented in the Roman Empire)
(** there are some exceptions. Costco's glass-bottle EVOO, which is sold only seasonally, seems to be authentic (at least virgin, if not EV), and sells for $13/liter)