During an overseas trip, usually the tour guide will arrange some visits to certain stores or tourist spots. Avoid buying tea at these places. Avoid buying tea from the sellers you come across in the street too, otherwise you may be cheated. If you really want to buy tea when you are travelling, you should go to a well-known or branded teashop. It is even better if the seller allows you to try brew and taste the tea. You should also be aware of stealthy substitution.