Learning to Differentiate Laowei

There is a lack of descriptive words for tea's flavors and scents in English, most likely stemming from a lack of translations for them. 

There are only a handful of basic taste categories that we experience.  Sour is one of them.  When it comes to tea, though, there are many different types of sour, both as sensations and as flavors.  Sour as a sensation would be like biting into a lemon and getting that puckery "damn that is sour" taste, accompanied by a scrunched up face.  Sour the taste could be like the tartness of a Granny Smith apple, or a balsamic vinaigrette.  Both are pleasant, both are sour, but also quite different.

Laowei, "old flavor," is present in many old teas.  It can be a good thing, such as the soft and gentle aroma (with just a hint of mustiness) that would accompany the breakdown of a fine oolong.  Or it can be nasty, like the foul decomposition of an old, improperly stored puerh cake.  Laowei as a taste may also have a certain characteristic flavor profile, such as the light and pleasant pluminess of an aged oolong, or the camphor-like quality of an aged puerh.  Or it may taste unpleasantly sour, like a bit of rancid goat milk been mixed in with the leaves. 

When I buy teas from vendors online that have written flowery, wonderful prose about the delights of their product, only for me to feel disappointed that my brew doesn't quite match, I'd like to know what I may have done wrong in my brewing or tasting.  I think the next evolution of tea tasting will be technology that will allow people to brew and drink tea with the producers or retailers online.