Thats what I was thinking.. it should be kept as clean as possible because we don't even know the true inhalation risks of traditional ingredients. Some chemicals change into toxic one's when heated/vaporized, and there's usually not many studies done (for inhalation) on products made for consumption. I've recently heard that vanillin is one of those ingredients, but it was just a post on a forum, not confirmed..
Also, because we hear of college kids dying from drinking alcohol with it.. it just scares me a bit. Abuse or mistakes are too easy, and it would hurt the community overall (imo).
Nicotine is dangerous enough, and the FDA is already all over the alcohol/caffine stuff, why add another ingredient they seem so interested to regulate?