It's not just your tastebuds soupor, of all the different tasteless e-liquids i've gotten, they all seem to have that bitter taste. Tastes like warm stale beer to me. It's something they put in their base, but I'm not sure what. The pure nic+usp pg stuff I got from bliplabs has almost no taste, and i've found it takes very little flavoring to make it taste good. Maybe that bitter flavor is the type of glycerin or something else they put in it, but mixing my own stuff and staying pure seems to avoid the problem altogether.
FYI my current recipe is 30% 7.5% nic+usp pg solution, 20% flavor, 10% glycerin, 40% USP PG. Omitting the bit of glycerin makes a stealth vape, when I exhale there is almost zero visible vapor, but the throat hit seems to be a bit decreased as well, so I added it back in.
Edit: I'm actually vaping the banana cream right now too, its awesome. The watermleon and tropical punch are pretty amazing as well. I've been switching between watermleon and banana for the past couple days, love the stuff.