I've recently come across this problem, I ordered kanger horizontal coils and the first two I filled up,(mind you I filled them and let them sit like you should) They tasted horrible and burnt, thought maybe it was the juice reacting differently to the filler, but tried a different juice and got the same thing on the third one. Those where on my 808 I use at work sometimes, Then on my ego c upgrade, I had to clearomizers, I think visions but they could've been knock offs, and those to had burnt taste. I tried cleaning them and dry burning from youtube videos and the coils don't even light up red so idk what my problem is lol