That's a really good point-- I strongly suspect that lots of the so-called PG or VG sensitivities/allergies might really be sensitivities to other substances mixed with them, like specific flavorings. Seems I've read several posts by people who thought they had a PG or VG sensitivity, but then found a particular liquid that works for them.
ECOpure is a good place to start, since Intellicig makes it themselves and keeps it as pure as possible. (Read about it here.) I'd suggest buying a little 3-ounce bottle of "Fresh" (unflavored) and see how that goes. I know that InnoVapor sells them for $3, but of course then you have to pay $5 shipping. (Actually, I guess you could use the INNOVAPOR10 coupon code to save another thirty cents!)
In any case, I find myself paranoid about "generic" liquids and Chinese-manufactured ones, because it's hard to know for sure what's in them. I like Johnson Creek, who make their own liquid and list their ingredients, and will be trying Intellicig's ECOpure next week for the same reason. Fingers crossed on the ECOpure, because after a month of trying several flavors and liquids, I'm pretty sure that I do have an actual PG sensitivity, and I'm hoping that ECOpure becomes my new go-to liquid.
Popped into the Innovator site - no impressed; say has limited ingredients, but only tell the 'main' ones. Just makes themselves look bad