Sorry i forgot to mention the most important thing about the subject.
But plz read carefully.
When you will visits different shops and will have chats about oils with owners, etc. After that when you will step out from the shop, you will be in position to recognize that this oil dealer sells original oils or fake.
Yaar, this is really something i cant explain in words exactly. But just a little fast IQ and bit use of common sense is enough to know about the quality of the products at that particular shop. Try it and am sure you will be able to make a quick decision by yourself.
just for the kicks, when i usually steps out from any unknown oil shop, i can really guess about the quality of the products they are selling.