Here's my take. There are FAR too many good, vapable juices out there to waste your time, taste buds or money on unvapeable juice. I just move on. Not much can save something that just tastes nasty. You can try steeping, as that does help some flavors, but usually initially nasty just turns into aged nasty.
I've been saving some of my less-than-good (to me) juice in the event I have a friend who gets into vaping, I'll toss it their way to help them along. I've thrown out a few entirely because I wouldn't even give some of that stuff to my worst enemy.