I've had cork on the brain of late. Despite that we found the lowest failure rate yet among natural corks for newly released wines in 2012, many potentially great wines end up spoiled in one way or another. With that in mind, it's worth pointing out that there are matters of etiquette when it comes to wines tainted by bad corks.
The most uncomfortable situation, at least for me, is encountering a corked wine in mixed company, that is, with strangers who are unfamiliar with TCA (2,4,6-trichloroanisole) and the myriad other faults that may lie in wait within a bottle of wine sealed with a cork. (It's awkward too if a guest has brought a special albeit flawed bottle, worse yet if you yourself are the bearer of tainted wine.) Some people choose not to say a word if no one else at the table seems to be aware a wine isn't everything it should be. I think it's imperative you point out the flaw and take the time to educate your companions.
The ritual of sniffing the cork can be educational as well. While the smell of the cork is not a positive indication that a wine is good or bad, many times a cork that stinks of wet cardboard or moldy newspaper serves as confirmation that an off-smelling bottle is corked. It can save you pouring out several glasses, or wasting time decanting a bottle only to have to dump the wine and thorougly clean the decanter.
And your fellow wine drinkers aren't the only ones that you should tell about a bad bottle. I suggest that when you encounter a corked wine you've paid for, you should inform the winery or retailer and seek a refund or replacement. Most vintners are keenly aware of the problems and happy to satisfy their customers with a replacement or credit rather than lose a repeat customer.
Wines tainted by bad corks make everyone uncomfortable. Many people are embarrassed or humiliated when they encounter a flawed wine, especially if it's their first experience. That's why it's important to let people know when a bottle is off, and educate them on how to identify a corked wine. A modicum of discomfort can become a learning experience for everyone, and illustrate why we wine-tasting veterans find the fallible cork such a frustrating closure.