Fault, style, or brewing
Three things can make a cup unsatisfying and they call for three different responses. A brewing problem changes when you change a parameter, so it can be tested in five minutes by brewing the same leaf differently. A style is a deliberate characteristic that you happen not to enjoy — a heavy roast, a deep steam, a piled shou — and it will not change however it is brewed. A fault is a manufacturing error, and it is permanent. The diagnostic order matters: rule out brewing first, because it is cheap to test and it is the most common cause, then ask whether what remains is intentional. There is a fourth possibility that belongs on the list and is frequently the answer: the tea is fine and old. Age is not a fault in manufacture, it is a fault in the supply chain, and it produces its own signature — flattened aroma, a papery or cardboard note, a cup that is technically correct and has nothing in it. Distinguishing that from a processing error matters, because one is the maker’s doing and the other is not.
Faults from the wither
A wither that ran too fast or too hot gives a flat, papery tea with little aroma — the leaf lost its water before it did anything with the time. A wither that ran too long or too wet, particularly in a deep unturned bed, gives a stewed, slightly sour, cooked-vegetable note. Uneven withering is the most common of the three and the hardest to name, because it shows up as a cup that seems to contain two teas: some brightness, some flatness, and a general lack of focus. If a tea tastes indistinct rather than actively wrong, an uneven wither is a reasonable first guess. Wither faults are also readable in the wet leaf, which is worth using. Tip out a spent infusion and spread it: leaf of one even colour came from an even wither, while a mixture of dark and pale pieces in the same lot did not. That check takes ten seconds, costs nothing, and answers a question that no amount of tasting the liquor alone will settle.
Faults from fixation
Under-fixed green tea is the classic and it announces itself over time rather than immediately. Some enzyme activity survived, so the tea keeps changing in the packet: the leaf dulls towards yellow-brown, the liquor darkens, and a fresh spring character turns into something vague and slightly sweet-stale within months. Over-fixed or scorched leaf gives a burnt, acrid edge that sits on top of everything and does not fade. And unevenly fixed leaf gives both at once. If a green tea bought fresh tasted good in April and dull in July despite careful storage, the fixation is a more likely explanation than the cupboard. The wet leaf helps again here. A properly fixed green tea gives spent leaves that are still green, sometimes vividly so; leaves that have gone olive, khaki or brown at the edges are reporting either incomplete fixation or subsequent oxidation in storage. Neither is recoverable, and both are worth knowing about before buying the same tea from the same source a second time.
Faults from oxidation and drying
An over-oxidised black tea goes flat and slightly sour, losing briskness rather than gaining depth; an under-oxidised one keeps a green, raw edge under the malt. Both are common and neither is subtle once you have tasted the alternative. The drying faults are the ones that show up latest. Under-drying is invisible on the day and is the single most common cause of a tea that has gone musty, stale or sour after a few months in a sealed packet — the residual moisture had nowhere to go. Over-drying gives a hard, baked, one-dimensional cup with the aromatics driven off. The asymmetry between the two is worth stating, because it explains why one is far more common than the other. Over-drying is obvious on the day it happens and somebody will be told about it. Under-drying is invisible on the day, saves time and fuel, and produces a fault that appears months later in somebody else’s cupboard, by which point nobody involved is in a position to attribute it. Faults with delayed feedback are the ones that persist.
Faults from storage, which are not the maker’s
Musty is the signature of damp, and it is worth distinguishing from the earthy character of a well-made shou or the cellar note of humidly stored pu-erh, which are different smells once compared directly. Flat and cardboard-like is oxidation and aromatic loss in a tea that was not meant to age — the ordinary fate of a green or lightly oxidised tea kept warm for a year. Tasting of something else entirely is odour absorption, and it is irreversible. These are the buyer’s or the retailer’s faults rather than the factory’s, which matters when deciding whether to buy from that producer again. The boundary between the two is genuinely blurred in one place, and honesty requires saying so. An under-dried tea and a badly stored one produce a similar musty result, and by the time it reaches a drinker there is usually no way to tell which happened. Where a seller handles their own storage well and the fault appears anyway, drying is the likelier culprit; where several unrelated teas from one retailer taste the same way, the retailer is.
What this changes about buying
Two things. First, it moves the question from do I like this tea to what happened to this tea, which is a much more useful question and one that produces transferable knowledge. Second, it makes stale tea identifiable as stale rather than as a category you dislike — and since a large share of the tea sold in general retail is old, that single distinction changes what somebody concludes from a bad first experience. A great many people believe they dislike green tea on the evidence of a leaf that was under-dried, under-fixed, or eighteen months past its best. A closing caution against over-diagnosis. Most disappointing cups are brewing, most of the rest are age, and genuine manufacturing faults are a minority of the total — so the diagnostic order in the first section is not a formality. Reaching for a processing explanation before testing a parameter is a good way to acquire a confident vocabulary for something that would have been fixed by using more leaf.