In the immortal words of Norm from Cheers, "Some days you're the puppy, and some days you're the newspaper."
It happens to all of us, though I've had a pretty good track record. In fact, I haven't met a corked wine in over a year. I don't know if that's luck or the fact that I've been drinking a lot of wines with screwcaps/synthetic corks/Zorks. But we all get burned occasionally. I did recently help a friend identify a wine that had a horrible brett infection, and I've come across one or two bearing that petroleum tinge that comes from processing in the wrong kind of plastic.
But the most common flaw you're likely to encounter is simple oxidation. Maybe a bad cork, maybe improper storage, or maybe it was just a wine that wasn't meant to age. The wine turns brown, becomes sour, and it's more like drinking vinegar than wine. The 2000 Georges Dubuf Moulin-à-Vent Prestige pictured here wasn't quite oxidized, but with another year or two it would have gotten there.
As of 2010 it was merely dead. Drinkable, but a ghost of its former self. An ex-wine, not even pining for the fjords. I could pick up a little cherry structure, a light and balanced body that would have been great five years ago, and the vintage charts claim this was a good year for Beaujolais. However, there's no reason to be angry or upset. Wine is sometimes a gamble, and I've had many more wins than losses.