Although it concerns a tea drinks chain, not a teashop selling leaves, it still sheds a light on how much fraud is going on in Taiwans tea trade.
Just look a this part of the article:
Imports from 47 countries! Sound very plausibly to me that a good part of that is also sold as Taiwan tea… Buyers beware.Chiang said Taiwan imports tea leaves and flower petals from a total of 47 countries, with those from Vietnam accounting for nearly 70 percent.