That makes me wonder if that other vendor is doing something to them, or maybe they've just been sitting for a while, because all the TFA flavors I've gotten, whether from BCV, ECX, WizLabs, or direct from TPA/TFA, have been thin -- they're in PG, which is almost as thin as water. I even wondered if you might be in a cold climate, but OK this time of year should be nearly as hot as it is here.
Some of the TFA flavors are sweeter than others; Vanilla Swirl comes to mind, and definitely the banana nut bread. I think the DX Bavarian is a bit sweet, but not as sweet as the Vanilla Swirl.
One thing I *have* noticed though; when I've bought the 4oz (120ml) sizes directly from TPA/TFA, they have a bit of an alcohol smell. I figured it's because they're fresher, so the alcohol smell hasn't had time to wear off. I last bought my DX Bavarian and Vanilla Swirl that way, and noticed the alcohol smell. I'm thinking that the fresher they are, the thinner and less-sweet; sweetener seems to "ripen" over time, becoming more noticeable the longer it sits. This effect is more pronounced in actual mixed ejuice, but I suppose it could also be the case with the sweeter flavors.
As far as I know, FlavourArt flavors are also in PG, so they should also be thin.
Andria