About 30 years ago I found an unopened bottle of Dom Perignon champagne, dated 1929, in a huge pile of trash removed from a house that was being vacated. I kept that thing like it was some kind of treasure until, a couple years later, my family was moving, so we opened it. No surprise, it had gone bad; in fact it tasted a lot like sherry, but not very good sherry. We poured it out. I would have been better off to leave the bottle unopened. ....
Wasn't there some story a few years ago where someone had bought some wine or something only to find out later that the bottoms of the bottles had been drilled and the original contents drained out and cheaper stuff squirted back into the bottles and then the small hole was filled with wax or something?
Always check the seal on the bottom as well as on the top.