One of those reviews is mine...
Not sure what info you are looking for exactly. The bottle I had was similar: unlabeled and dusty, the only identification was a DN 91 someone had written on the cork, although I have no idea at what point in it's history that happened. It seems likely to me that this is one of those beers where a couple cases surfaced out of someone's cellar and have been trickling out, given the dominance of the 1991 vintage in reviews.
Of the really old gueuze I've had, it was certainly the best, although I can't claim to be particularly experienced in this arena.
Finally, I leave you with these two reviews, which I find oddly more similar in style than I would have expected:
http://dontdrinkbeer.com/2013/02/11...eer-that-is-older-than-your-girlfriend-sicko/
http://www.beerhunter.com/documents/19133-000015.html