If you drink wine you will encounter flawed wine. It is a fact as predictable as death and taxes, though easier to miss. You can refer to my earlier post about how to identify bad wine for some tips and assistance on that front.
But, what do you do with bad wine?
Easy, return it. Take it back to the place you bought it and ask for a replacement bottle or a credit to spend on something else. If you don't remember where you bought it you can find any retailer that currently sells the wine and return it there. It will not matter to the wholesaler which outlet returns the bad bottle to them. Distributors supply the local area, often an entire state, so a bad bottle would come back to them no matter who returns it. They will then either issue a credit or a free bottle to the retailer to replace the bad one.
As an aside, some importers and wineries do not replace bottles for the wholesalers but that should not concern you, the consumer. Usually in these instances, which are rarer and rarer, the importer provides an allowance in pricing to account for samples and bad bottles. In the end, wine wholesalers know bad bottles exist and that they are returned, so if they don't negotiate properly on their own behalf it is not your problem.
Now, for your duties in this matter. Be sure the bottle is bad. Too many bottles make it to the wholesaler that are just wines the customer did not like. While it is unfortunate if you buy a bottle that does not please your palate, your dislike is not a reason for a return. You can can bring a sweater back to a store but once a wine is opened, it can't be resold or re-gifted.
Helpful Information/What's In It For You
If you are unsure, return the bottle as soon as you can (the next day is ideal) so the merchant can determine if the bottle is bad or just not your style. They might offer you a replacement either way but you will learn the difference. As an added bonus, if the wine is fine but not for you, the merchant will have learned more about your palate and can make better recommendations. Good luck doing this with a chain retailer.
On the plus side, for consumers, many of these retailers have very liberal return policies. I know of one that accepts them, no questions asked. You might be able to taste your way through dozens of wines to find just the right ones while returning all the others. This is not a recommendation, by the way, just an observation.
Sorry, Too Late
If you have had the bottle in your possession long enough that is is no longer the current vintage, the retailer has less obligation to make it right. Your storage conditions may not have been ideal. If the bottle is obviously corked, good merchants will likely take care of you if they still stock the wine. If the bottle is more than four or five years past vintage you can forget it. If you find retailers willing to accept returns of wine that old, let me know, I may have some bottles for them.
Dining Out...and Refusing Wine
Restaurants are a similar, but different story. If the bottle is old and corked, they must accept the return as they are the ones offering it for current sale. They may be stuck with it then but, again, that is not your problem. They wouldn't force you to buy fish that doesn't taste right just because you ordered it. In restaurants where they age bottles on site, there is always a sommelier or wine person you can talk to about the condition of the bottle, both before the bottle is opened and after if you are unsure or unhappy.
Traditionally, to verify the quality of the bottle about to be served, someone on staff used to taste the wine before pouring it for the diner. That practice has all but vanished but if you have concerns, invite a knowledgable staff member to taste the wine. Don't worry, they will only pour a little.
Don't Be These People
I once walked into a restaurant and had three bottles of the same wine sitting in the return area. I asked what happened and the manager told me that she had been off one night and a new member of the waitstaff kept opening the same wine because the customer said it "didn't taste right." He claimed to be a fan of the wine and bullied the waiter into bringing the same thing again and again and again.
I have also witnessed this as a power play. Returning a dish or a wine or otherwise demonstrating your dominance displays strength to the rest of the table and perhaps the restaurant. It also is a complete jerk move and burdens a wholesaler or a winery with an economic loss because someone was out of his Viagra or otherwise lacked confidence.
Take This To Heart
One more recommendation, be polite about the return or refusal. Instead of pontificating, present it as a question or gentle approach. "I think this might be corked" or "Do you think this tastes the way it should" will go a long way to getting you what you want.
Remember there will always be wines that are flawed. There will also always be wines you do not like. Engage your waiter, sommelier or retailer and you will not only learn the difference but you will gain more confidence and be more likely to find wines you like in the future.