Matt Kramer has an article on wine etiquette at Wine Spectator:
The dinner party started smoothly and we all seemed to be enjoying ourselves. But when the first wine, which our hosts were quite proud of, appeared at the table it was unmistakably (to me, anyway) corked. But nobody said anything.
Here lies the dilemma: In such a situation, do you say something? Or, even though you are sure you’re correct, do you keep your gob shut? (As you might imagine, I often have a problem keeping me gob shut.)