I think, as you suspect, it has to do with both the frequency of re-roasting and the storage conditions.
So perhaps it is what you could call "wet stored."
I had a very curious aged baozhong that marshaln picked up for me in Taiwan at the infamous "candy store" that I really wish I had a little of to send you a sample of. It clearly had been roasted fairly strongly at some point, but it had maybe not been stored super carefully, and probably hadn't been re-roasted much. It didn't have too much of a musty taste or really any sourness. You could still taste the roast in the background, but not in an unpleasant way. The taste was very curious and hard to describe. Some people immediately liked it, and other people didn't like it at all. When I first tried it, I wasn't sure if I liked it, but then I started to crave it randomly, which I always think is a good sign in a tea.
Hehe indeed. There's lots of teas that seem great, but not as many that I randomly crave.
That does sound interesting, though. In a way it sounds a little like what I have here, but perhaps mine isn't quite as interesting.
I've heard that you can't roast out storage problems, but it would indeed be interesting to see how it changes it. I plan on using Imen's method with the folded paper "scoop" over a stove on medium heat on the 58 Bai Hao. Maybe I should try it on this odd baozhong and/or 20 yr dancong as well, just to see how it turns out.
From the various aged oolongs I've tried, I think it's fair to say that (aside from ones which have gone too sour), they generally fall into either a more "sweet" flavor profile, or a more "earthy" one. Presumably, the more earthy tastes would come from a tea aged with little or no re-roasting. I'm not sure if a roast just long enough to take out some of the moisture would prevent the development of this flavor.
I hadn't really thought about that. Some of the mentions of roasting seem to indicate that that's all that's really needed. I imagine that's a subject that would take a lot of experience over a long period of time to really understand.
Honestly, there are so many variables involved that I don't think you can really predict how an aged oolong will taste; the best thing is to just try some and see. If you're aging your own, you can taste a little every couple of years and make sure it's progressing without any odd off flavors.
Maybe I'll have to get some of those nice ceramic canisters to seal with wax :)
BTW, try Stéphane's '76 baozhong - I think it's a pretty good / well balanced example. He had an early 90s ('91?) dong ding that was also phenomenal, but I don't believe he has it anymore.
I have it, actually, along with the 60's one he had :) Red Blossom's 82 is pretty good too. I just tried a bit of Camellia Senensis Tea House's 85 and that's actually the best I've had. They gave it to me as a sample (a generous sample at that; the sample usually costs $10), but I definitely plan on buying a good amount.
Some of the lighter Taiwanese teas taste great if they are kept really well sealed... they keep that lasting aftertaste, but pick up a little sweetness and mellowness.
I actually just got my first taste of some greener aged oolongs in my shipment from CSTH - they really are quite impressive. Mostly like the greener oolong, but with a more "solid" base and structure that's hard to describe adequately.
re: sourness, I don't personally agree that a properly aged oolong should have much sourness. I don't mind a little, and I can take more of it than some people, but I have seen one person say that an aged oolong *should* have that sour-plum taste, and I am not so sure about that, at least if you're drinking it for the taste, and not for the... uh... medicinal effects.
I've actually been lucky in that I have yet to really encounter a sour one yet. I'm sure I will at some point, though.
Just to be sure, the "plum" taste I mentioned is just that sweet musty-woody-fruity character that only seems to come with age. It's hard for me to really define, but "plum" kinda sorta comes close. I have gotten a new futon couch (rubberwood frame) and coffee and end table set (birch) that have a fantastic odor by themselves and even better together - almost like an incense of quality I've never encountered. The two together are actually very similar to this smell, but without the fruit (they're not musty either, but perhaps a little hint of something like a musk incense - you'd have to smell them to understand... I wish the smell would stay forever).