"Electronic cigarette advertising levels have not been particularly high and it is not clear how substantial youth exposure to such advertising has been. Another plausible hypothesis is that it is not advertising of the product, but general exposure to the product through the media that has contributed to youth awareness of and experimentation with the product. For all we know, more youth saw Katherine Heigl vape on Letterman than have ever seen a Blu advertisement. (This is a testable hypothesis, by the way, but what is the point of testing it since a conclusion has already been drawn?)"
"This appears to be another example of tobacco control practitioners disseminating the answer to a question before we have conducted research to provide an evidence-based answer. Does the answer really matter? It appears not. It appears that a pre-determined ideology that opposes electronic cigarettes is leading us to draw conclusions on the product without evidence. The CDC has already disseminated the conclusions that e-cigarettes are a gateway to youth smoking and that advertising is responsible for this effect, even though there is absolutely no research on either question."
At least the article delves into how this issue is being decided in a political and ideological way. Better than most I've seen linked to.