I just got my gear in and the Test Enant, is from a Mexican brand. From what I've quickly researched the company went out of business years ago and the distribution rights were sold to a Chinese firm. The bottle itself looks legit, but the top is matte gold. Bottom says :
When a drop comes out of your needle (when pushing the air out of the pin), pick it up with your finger and put it on your tongue. Testosteron should taste like some kind of vegetable oil BUT it will tingle on your tongue.
Sounds nasty, but hey, admit it as a youngster you tasted your own semen too didn't you? DIDN'T YOU?
I could be wrong but I believe the "tingle" or "burning" is from benzyl alcohol rather than Test...granted, totally fake gear might just be some sort of food oil without any BA, but I'm just saying I tend to doubt that there's any way to confirm legitimacy just by taste. The only real way (as another mentioned) would be to have it sampled at a lab, but I have no idea as to the legal or practical issues behind that...are there legitimate labs that are willing to receive controlled substances from a regular citizen? Seems unlikely.
In that case, the only practical ways are to do your best to know the source, and see how it goes in terms of results and sides.