Yes, vape juice can go bad. However, it takes a very long time for this to happen. Vape juice degrade slowly over time, so they don’t suddenly become unusable on the exact date shown on the label. Instead, the best before date indicates when the juice is likely to start degrading.
Most vape juice have a shelf life of around 2 years from their manufacturing date. However, this can vary slightly depending on the formulation used. For instance, nic salt E-liquids degrade slower than freebase nicotine E-liquids. In addition, fruity flavours degrade quicker than more complex flavours like desserts.
The storage conditions of your vape juice can also affect how quickly it degrades. If you store your vape juice in a cool, dry, and dark place with the lid closed, they will probably last a long time. On the other hand, if you store them in a warm, damp, or bright place, or leave the lid off for a while, the juice is more likely to go bad.