That bad taste usually caused by of three things:
If you are using cartridges, strands from the filter inside the cartridge fall to the atomizer and burn, which then produces a bad taste or smell from the atomizer. You should remove the strands with a toothpick and clean your atomizer.
You are low on vapour liquid and you are running the atomizer dry. When you run your atomizer dry, the wick inside of the atomizer tends to burn and once that happens, it then produces a bad taste. You should clean your atomizer and ensure that you keep the atomizer moist with vapour liquid.
Or your atomizer needs to be cleaned. Vapour liquid does buildup on the atomizer and your atomizer “gunks up” and and the liquid sticks to the inside the housing. Try blowing through the atomizer with your mouth to break that gunk up.
In a nutshell, it is likely that your atomizer just needs to be cleaned. There are many videos and information pages that explain how properly to clean your atomizer.