The most disgusting, nauseating, and downright offensive e-liquid experience I ever had was with Johnson Creek Original Smoke Juice. The weird thing was that it smelled pretty good out of the bottle, but then I started vaping it.
I know taste is subjective and yadda yadda yadda...but this juice was filthy. Things like castor oil, catpiss, and burnt dust coming from an A/C heater immediately came to mind. It's as if they used "naturally extracted" ash as an ingredient.
Needless to say, after vaping it for an hour trying to give it a chance, it made me sick to my stomach. Nothing I vaped or smoked afterwards could remove the revolting aftertaste that stuck with me. Only a good night's sleep could help me recover.