It is a safe bet that every western household has at least tomato sauce or mustard in their kitchen. The definition of a condiment is one which is added to a dish to add or enhance its flavor. It can even be considered one which completes a dish. This is not exactly a giant leap in logic. Consider the last time you ate a hotdog without adding ketchup to it. Or eaten a corndog that was not laden with mustard.
These ingredients, which are included to elevate the taste experience, obviously need to retain their flavor. A flavorless additive is completely useless. Ketchup which does not taste like ketchup anymore may as well be thrown in the bin unless what you are looking for is slightly red tainted food.
To save money, some households buy products like this in bulk. This is not necessarily a problem, but it should be noted that these cannot be stored in a pantry indefinitely. Even if the bottles are still sealed, leaving them at room temperature will diminish the taste over time. If possible, it is best to store them in the refrigerator.
The same is true for condiments that have been opened. Unless you form part of an extremely large family or are involved in the catering business, condiments are not opened and finished in the same sitting. They are kept open for a few weeks or even months. Once these condiments have been opened, they need to be placed directly in the icebox immediately after use. This will increase their shelf-life and maintain the intense flavor of the product. By storing these products correctly, they can be safely consumed for months without any lessening of their flavor.