That really is a very good question. Actually it can be extended to question all teas of origin. However, let me answer it specifically first.
Wuyi style oolongs are produced not only in nearby areas, but also in other tea regions, some even outside of Fujian. I cannot tell the difference by just looking at them. However, the taste tells. So what is it in the taste that marks the difference? How would you describe the difference between Yosemite and a neighbourhood park, or your backyard, or a run down lot in a bad neighbourhood? Or how would you describe the taste of a fine Kobe cut from a MacDonald burger “beef”? You won’t know it until you have experienced it. Beautiful poems, stunning pictures and hundreds of books are never nearly half as good as being there. That is the difficult part of word communication. Reality is so much beyond the capability of the language.
Back to the real issue. There are merchants selling other productions as Wuyi. Some even in shops in tourist shops in Wuyi itself. Price is not a guarantee and neither is this or that Chinese government label (trusting any Chinese government certification is like trusting any used car dealer). However, once you have properly infuse a genuine fine quality Wuyi Shuxian or the likes, you’ll know there is a distinctive taste that differentiates a Wuyi from others. Most others.
I know there are very good tea regions now attempting to make high quality production to compete with Wuyi. First lots are very convincing, but with their own finesse.
Note also that even within Wuyi, there are many, many different qualities. Wuyi is not a very small place. Sometimes a real Wuyi one is not as good as a good imitation.
As for the rest of the imitations, please judge it by the price-quality rule. You are buying a drink after all. If you think the difference does not matter to you, don’t pay for it. If you think you have discovered a very distinctive quality, enjoy it. But don’t cease to explore. It took me many years. I believe it’ll take you perhaps the same time as well.
