An interview with Robert H. Dick, official U.S. tea examiner before the Tea Act was repealed in the 90s.
Interesting stuff. Around page 30 he goes into the difficulties coping with Pu'er, and the resulting smuggling that happened.
RD: Most of the Chinese invoices will come in and they will just list "tea", and it can be just about anything. You really don't know what they do have. I am sure that a lot of the teas are coming in and are not being recorded or else they are coming in under another name because there are these types which we would reject because of the fact that they are very musty in taste. But they are very highly prized and highly priced in the Chinese community.
Also, before the 1970s, Earl Grey had to be flavored domestically, tea was not allowed pre-flavored into the U.S.
RD: Until we had the flavored tea and the scented tea standard, we would reject teas that picked up an orange flavor, for instance. We had one case where the tea was shipped with some oranges and it picked up the flavor and was rejected. There's a story about that too. The person who bought the tea decided that maybe people would like flavored teas and during the '60s and '70s they started bringing in teas that were flavored that way. However, we would reject them as containing foreign flavor until along in the early '70s we had a letter from the legal people in Washington that we couldn't reject it because people in this country were flavoring the teas the same way and selling them here on this market. They said we were discriminating against foreign suppliers. [. . .] So we set up two additional standards at that time, one of them for scented teas, which just have the flavor in them, and one for spiced teas which have things like various spices, cinnamon stick, cloves, orange peel, lemon peel, or something like that. They have become a fairly large item on the tea market.
Also a fun anecdote about radioactive Tetley tea. Lots of fun stuff, give it a look!