Wine Faults
Corked Wines
Oxidized Wine
Contamination caused by too much oxygen exposure, like a sliced apple turns brown, reds will show a brownish tinge. White wines are much more susceptible to oxidization than reds, because reds’ higher tannin levels act as a buffer.
2,4,6-Trichloroanisole (TCA)
A chemical contaminant that found its way into your bottle somewhere in production, usually from real cork. TCA can be present in oak barrels, or the processing lines at the winery as well, which leads to entire batches, rather than single bottles, being ruined, has a dank odor and taste like wet newspaper, moldy basement or smelly dog.
Sulfur Compounds
Some sulfur (sulfur dioxide or SO2) is added to almost all wine to wine stabilize it, and manifests as a smokey, struck match aroma. The most frequent manifestation of a sulfur-related flaw is mercaptin, a rotten egg, fart, burnt rubber, or skunk smell.
Secondary Fermentation
Tiny bubbles in your wine where there shouldn’t be any, especially in a young bottle of redwine. This usually happens when the wine is accidentally bottled with a few grams of residual sugar and then re-ferments. This most frequently occurs in low-intervention winemaking, where little-to-no SO2 is used. Some winemakers will use it to for a little pizzaz, and some styles are naturally frizzante such as vinho verde or some gruner veltliners.
Heat Damage
Wine ruined by exposure to too much heat and the wine smells jammy, sweet, but processed. The smell is somewhat like a wine reduction sauce, mixed with a nutty, brown, roasted sugar-type aroma. Heat damage often compromises the seal of the bottle (the expansion from the heated air pushes the cork out) so it can be accompanied by oxidization.
Volatile Acidity
This can be one of the most common wine faults, known as vinegar taint, but it is also a tool used by some high quality winemakers to develop complexity in their flavor profiles; Some is a wine making fault; an accidental or inadvertent overdose of acetic acid.
Tartrate Crystals (not really a fault)
These are mineral precipitates that form out of unfiltered, high mineral wines. They are little crystals sitting on the bottom of older bottles.
Herbal Aromas
Herbal aromas are typical parts of certain varietally-specific flavor profiles that can smell of grass, eucalyptus, or asparagus. The most common of these chemicals is methoxypyrazine or “pyrazines” for short, which are commonly found in Bordeaux-family grapes. To new or unfamiliar wine drinkers, these aromas can seem like wine faults.