Do the fruit-flavored tobaccos that are widely used in hookahs require a Kashrut certification similar to foodstuffs? If yes, why; if not, why not?
According to the cRc they probably do. However I disagree. Se what I have written here. The same argument applies here as well, except with an added leniency: You don't know whether there is non-kosher stuff inside there, and even if there is, it is mixed into the tobacco and unrecognizable. Thus it could be said that even the Rema would agree to be lenient here l'chatchila. For further elaboration, see what I have written in this blog post.
The question is if the vapor is considered zeah (steam) assumably the discerning factor would be if the vapor would turn into moisture upon its settling on a surface. If it is considered zeah than it would seem that the taste infused tobacco would need a hechsher. The Hookah acts as a mini oven where the Reach (lit. smell, it refers to the non-moistured particles of food that spread throughout the oven during the cooking process here it would refer to the smoke) is passed through the water (which smoothes out the smoke) and then is inhaled via the pipe. If the tobacco is not kosher than the water becomes not kosher (the water is rarely 60 times the tobacco). Even though intaking Reach is not considered halachikally eating, assumably intaking Zeah (which is considered of substance) would be. Therefore, the relevant question is if the water that becomes part of the smoke that is being consumed, is considered zeah, or not. This seemingly is not such a hard experiment to run. All one needs to do is to drag on the pipe of a hookah onto a surface and see if moisture forms.