Just to say, I went cold turkey off analogs WITHOUT vaping for a total of 30 days. Not one thing with my health changed other than coughing less. I vaped a Blu (where the cartos tasted like burnt metal) other day and suddenly my cough is coming back (not as severely.) It may be a blessing that the charger pack broke 6 days later.
About a year ago, after vaping some burnt tasting cartos from Revolver, I had a severely damaged, sore throat for a week, severe pain. Another time, a off-brand disposable from a store gave me canker sores galore.
Honestly, my suspicion is that it could either be the wicks, what happens to the wicks if they burn, or chemicals in the e-juice... what else could it be? Burnt (possibly even non-burnt)!silica wicks have been shown to release spikey silica particles in the vapor; these could possibly break the skin in the mouth, causing sores, and cause irritation in the throat. With e-juice, if it's from overseas, no telling what's in it.
I'm sticking to tanks that I can see into and juices made by companies that present a more professional vibe than having some juice that's called "Orangalicious Outstanding Orange 7UP Badazzle Dream God Bless America", with graphics that look like a discount tobacco shop.