In aroma: The International Magazine for Essential Oils, an article about the perpetual popularity of Lavender oil reveals that "Domestic consumption and export of Lavender oil far exceed the amount produced by agricultural methods. It has become profitable to mix less expensive essential oils like Lavandin or Bulgarian Lavender (from clones) with synthetic linalool and linalyl acetate and to offer the resulting "bouquet" as True Lavender."
Apparently the president of the confrerie de la lavande said that although Provence produces about 50 tons of true lavender annually, brokers export 250 tons, and he humorously called this a greater miracle than the ones of Lourdes and Fatima.
I can understand why there are strong warnings about using essential oils, and strong recommendations that they be applied topically only: we don't have a clue what is in some of them. That is, unless you have a reputable vendor of genuine and authentic oils.
Over time I have learned about some possible signs of fakery: if the price is too good, it's probably too good to be true. :) Sometimes the aroma itself is too good to be true, or has a solid perfumy smell. But these days, adulterers (ain't that a great word) are smarter and smarter, smarter than my nose and ability to do math.
So I continue to read up about suppliers, try to educate myself about the oils I'm purchasing, so that I can use Lavender with confidence and safety.
From Monica Haas:
How to spot fine lavender made by Nature!
Linalool and Linaly Acetate never more than 80%
Lavandulyl acetate at least 4.5%
Cis beta ocimene and Trans beta ocimene > 0.5%
Camphor below 0.5%