Here is what I can say as someone who has been at this for over 30 years.
Anyone who has been in this game for a while can discern real from fake on certain drugs.
The two that come to mind are Deca, Nandralone Deconate and D-bal tabs.
The reason these two are so easy to authenticate is the taste.
There is nothing else quite like it.
Dbal has a very bitter medicine taste that if you have a baseline reference, you will always know if its real as nothing else tastes like it. obviously you cant tell much about potency but, you can tell if your dealing with the correct chemical.
Deca, is easy too. Put a few drops on your tongue. Once again, the tasted is very distinct.
Its a strong, medicine taste that will numb you up and make your tonque feel numb.
This taste is also very prevlent sometimes when you administer the injection and after a few moments, you can taste the same taste in your mouth as it circulates in your blood from presumably hitting a blood vessel.
I've had this happen dozens of times.
if it takes very benign and like nothing but oil, it probably is nothing but oil.
Hope that helps chief