Identifying specific problems in their methodology isn't dismissing good science out of hand. In fact, it's exactly the opposite. You've already judged it to be "good science" when the study hasn't even been independently confirmed. Note that I haven't made any claims about their hypothesis. There very well could be some of these negative health effects found in future studies that use better methods to confirm it. The study could also be wrong for many reasons. The implication that the results apply to ecigs in general is ludicrous based on their complete lack of evidence to support generalization of the results for two product formulations. That NJOY product could have many other ingredients that are entirely responsible for the results they observed, and they did nothing to help narrow the possibilities. I'm reserving my conclusions until there's much better evidence than this.

You also claim that they were attempting to account for dry hit conditions. Precisely where do you see the evidence for this? I don't see any such evidence in the study, such as measuring for the degradation byproducts due to excessive heat. The amount of free radicals isn't necessarily such a measure because this could be due to any of the ingredients in the flavored ejuice regardless of the vaporization temperature. The blood level of cotinine also isn't a measure of dry hits, since nicotine is still present in dry hits. They specifically said that they weren't measuring the quality of the vapor during the exposures. I'll take their word for that.

That they found far fewer free radicals in a sample of the vapor compared to cigarettes is slightly useful information, but I don't entirely accept that result either. There could be different results found in other kinds of ejuice, and it could be due to the flavorings or other ingredients that aren't shared by most products. If it was due to PG, VG, and/or nicotine, this study doesn't help to determine which because they didn't test them individually. Picking a juice with a lot of ingredients isn't helpful to narrow the potential causes for a specific effect. Picking the simplest compounds possible would be much more useful to identify the causes. One of the inherent advantages of testing ecig vapor is that it's possible to create a liquid with very few compounds, unlike tobacco which contains so many. Yet so few studies take advantage of this fact to use a minimal number of ingredients instead of liquids that have...who knows what in them.

Do you know all the ingredients of those NJOY products? I don't. NJOY doesn't list them. Do those researchers know? There's absolutely no evidence that they do. Doesn't that seem to be rather foolish, to select a liquid for a study like this without knowing what's in it? It's not as if NJOY and all ejuice companies make their liquid by harvesting the sap of the same kind of ejuice tree. Their liquid is a unique formulation of some kind that only they know, and they aren't telling how.