If a cartridge does not produce steam even after changing the battery and even if the distillate is visible inside, there may be a problem with the atomizer or some other component. Cartridges that produce unpleasant tasting smoked vapor, on the other hand, should be considered empty and can no longer be used. Once the tank or cartridge is completely empty, you may see a few drops on the side of the cup. That amount of e-liquid isn't even enough to create a small cloud.
With the e-liquid, once it goes, it goes away. It is best to replace the cartridge or refill the reservoir.