I learnt the hard way when I also got that real bad toxic taste in my mouth. Trick is to keep topping up so you don't burn anything then the cartos last quite a while. I pulled apart the bad tasting one to see what was causing the smell and found that in between the wick there was a burnt out block of something (is this what is called the bridge?) Anyway these were Greensmoke Cartos which i'm still using now until my V4L arrives.