I dont know where you have been buying your lambics, but I have NEVER encountered a lambic that had turned to vinegar. Maybe your threshold for acetic acid is lower than most because a little bit of vinegar is acceptable in a lambic, it's caused by acetobacter, a naturaly occuring microorganism in spontanious fermentation.
Oak tannins should not be present in lambics, the foudres (large oak casks) used by many lambic producers are often upwards of 100 years old, the casks are also generaly retirees from the red wine or port industry which sells off its barrels when they lose their "red wine" taste. Thus, they have long since been leeched of (nearly) all their tannins. That is not to say that there are no tannins whatsoever in lambic, but they do not make a significant contribution to the flavor profile, and any tannins in the beer probably do not come from the oak casks.
Cheeseyness from hops is considered a fault in Lambic, Cheeseyness comes from using hops that are too young (still aged, just not long enough) proper lambic hops will have very little cheese left to them, and what is left will be driven off by the long boil.
Hate to call you out, but I also hate to see people spreading false ideas.
Phew! I'm glad someone called me out. {Insert Melodramatic Rant}
Wait, you called me out? *shrug* You corrected my limited first-hand knowledge and added to it. I have had little opportunity to coordinate my limited beer pallet with other people and have had only one person to coordinate my observations of Lambic with. I appreciate your correction. Thank you.
On the other hand. You have created some questions for me.
First, I have only managed to find non-fruit Lambic at two places in my area. One is Whole Foods and the other is a local beer shop. At both places it was outrageously expensive for a small bottle - typically $18. Twice at Whole Foods and once at the beer shop I purchased and it was vinegar. I admit, I did not buy it again from Whole Foods and I did take it back both times (much to their grumbling about how it was supposed to be vinegary). My point wasn't that it was vinegary, but that it was vinegar. I have purchased non-fruit Lambic from the beer shop four times now. The first time was fine, the second time was vinegary, and the other two times were fine. So, this brings up one question and one short story -
Every time I have purchased non-fruit Lambic there has been mold [or something growing] on the cork. Initially I thought this was due to bad conditions while shipping. However, as it kept happening, I did some Lambic research and came to the conclusion that this was acceptable if it had not been pasteurized. Is this correct?
Oh, and I just went and looked at one of the old bottles I have lying around. It was a Geuze, does that make a difference? I thought that was just a Lambic blended with younger Lambics, is this correct? Or am I wrong again?
Now, the story. So, the second bottle I bought from the beer shop, was super-vinegary. The first was good, a slight touch of vinegar and sourness, but not super-vinegary. I took the second bottle back to the shop. They insisted that was how it was supposed to be. I said okay, I accept it is supposed to be vinegary to some degree, but what pH should it be? After some fiddling around, looking things up, and reading, we found it should be between 3.2 and 3.3. So, I suggested we test the pH of what was in the bottle and if it was below 3.2 by any significant amount they should take it back as it was definitely vinegar, otherwise I was wrong and had a new flavor to learn. So, we did. Results? Well, they returned it, I got a new bottle, tested it right there and it was 3.2 something [thank you digital pH meters] and the new bottle tasted good. But the returned bottle? Yah, it was 2.7ish. Not much lower by number, but enough that it was very definitely vinegar not Lambic. By the way, the shop did taste it after that and agreed the flavor was off - that is, it tasted more like vinegar than Lambic.
Something I learned later, is that the steadily falling pH of Lambic is what affects the various stages of fermentation. So the active bacterial or yeasty beasty is related to the pH at that time. I have no idea which one goes when, but that is what I recall reading. Please correct me if I am wrong on this.
The other thing is why would Lambic change to vinegar as it is shipped to the U.S.? I have no idea. Further fermentation? Infection by something else? Bad storage? Water loss? Old? Who knows, I am happy to hear other ideas on that one.
And, let's be honest, it really isn't that big of a step from Lambic to vinegar, but it is enough of one that they just don't have the same taste.
Now, I did not know that they used ancient oak barrels. That is awesome. And I see where I had a misconception on the origination of the tannins. However, my understanding is that Lambics typically do have more tannins than other beers. So maybe they are getting the tannins from the hops or something else. There are a lot of sources for tannins, so it could be coming from nearly anything I would think. For example, many people assume that the tannins in red wine have to come from Oak, but they can also come from the grape skins. Some ones that are not stored in Oak, and do not have added tannins, do get it from their grape skins. At least, that is what I have been told [again, no formal education on this] by a vintner.
So, I was wrong on the source of the tannins. Thank you for correcting that. But, am I wrong in my understanding that they are more tannic than other beers and that this does add to the dryness, more so than other beers? I was thinking more tannic dry than tannic flavor when I made my earlier comment ... If it is more tannic, then where are they coming from? The aged hops? I wonder how many hops they use in comparison to most recipes ...
Cheesey Hops. Cool. I admit, I never really tasted the cheeseyness, that is something I have heard other people complain about Lambics, saying "they're always so cheesey" and I made the miscalibrated assumption that was from the aged hops ... since old hops are a cause of cheeseyness. It is good to know that is incorrect. So, is that to say that once hops are aged beyond a certain point, they start to lose their cheeseyness?
And that sums up my questions.
Thanks!