Test How It Smells
The most obvious way to tell if your perfume has gone bad is to test its scent. Some perfumes may contain vegetable oils which are known to expire over time.
If your scent contains no fat (like in the case of essential oils), it will last longer. If your perfume or cologne smells of vinegar or you notice a significant change in the concentration of the original scent, it might be expired.
It’s also likely expired if the scent is significantly different than the one you started off with.
See How It Looks
Generally, the easiest way to determine the quality of a product is by closely observing the colour. Just like banana peels, a perfume becomes darker in colour signifying it has gone bad.
If you started out with a clear or translucent gold liquid and you now have a more opaque or amber liquid, that could be a sign it’s expired.
Over time, scents with large alcohol concentrations may evaporate. An expired perfume will often have less perfume in the bottle than it did the last time you checked it.
Check the Expiration Date
It is very important to keep the box of the perfume because many times your perfume will have some sort of expiration date on its packaging. This can come in the form of either a batch code or a PAO (Period After Opening) number.
These are typically found on the bottom of the perfume or printed on the box it comes in.
There are often many other numbers like the catalogue number and bar code that are also printed on the packaging. It’s important to know which number you are looking at to determine if your perfume is expired.