Unlike wine, whiskey doesn’t continue to age so there’s no demand to cellar a bottle of whiskey to improve its flavor once bottled. Because of its high alcohol content, whiskey infrequently expires. Nevertheless, extremes in improper storage temperature and other factors could create the whiskey to deteriorate over time and, in rare cases, become undrinkable.
Look for changes in colour. Over time, whiskey can oxidize, causing color changes and changes in flavor. While not generally an indicator the whiskey has gone “awful,” oxidized whiskey can lose a number of its own complexity and be less gratifying to drink.
Save the date that the bottle was opened on your own calendar. The pro opinions differ marginally, but it is normally agreed that a bottle of whiskey must be completely consumed within 1-3 years, with some experts saying that noticeable loss of flavor can happen as early as one month after opening. This flavor decrease is due to whiskey in the bottle to a higher ratio of air as the bottle gets closer to empty, so the action of saving the previous couple of fingers of a whiskey that is very good can cause the whiskey that is nice to taste lousy more fast.
Compare the whiskey you’ve got at home with a new bottle of exactly the same variety to learn in the event the whiskey has gone bad or experienced a decline of flavor.