If that was the case I wouldn't have a chance and I would have to grow and distill all the oils I supply, which is almost impossible. There are so many cheap, natural and synthetic chemicals on the market, so many year to year and origin to origin variations in essential oils, that sophisticated criminals can fool the best. If we think the best possible way to go down is the Pharmaceutical route, then we would be fooling our selves, as this would lead to standardization, which in my book is adulteration. I believe nature should be left alone, as essential oils are evolving. We all know the strongest are the most diverse in nature.
Plants are weaker against attack when they are standardized.
People and animals get weaker when they are in bread. What makes us think eliminating changes in an oil, add this and that so they are always the same is any different for what most people know essential oils are for. Have a great nose for the oils you purchase. Run as many known origin - distillation samples as possible to judge against. If after all this you even slightly suspect adulteration, synthetic or not, put sample in suspect archive and don't waste any more time.