I just completed a most interesting experiment. Some years ago I bought a craft vodka, one of the early efforts. Despite the name vodka on the label, it had odors I'd call congeneric with an almost solvent-like taste. I really couldn't use it in this form. I decided to put it through the Brita I use to filter water for coffee. The first effort reduced the objectionable taste and smell by about 70%. The second run took out about 20% more. Interestingly, the texture on the first run was better, smoother and more aromatic/tasty. The second run made it a little angular in texture and a little unbalanced, but that's okay, it is otherwise very close now to neutral vodka which is what I wanted.
Activated charcoal treatment clearly works to remove or reduce significantly off-smells and tastes in white spirit. The reason I say white is, any brown spirit put through this will clearly lose a lot of color and barrel taste, so I wouldn't try it with that. But the Brita is brilliant with a congeneric white spirit. I'd advise it for any white whiskey you have around too that you can't drink on its own, or even brown spirits possibly where you want a more neutral taste and aren't fussy about the color and oaky taste.
True, I could have bought a commercial vodka for half of what I paid but this way I salvaged a bottle I otherwise would not have used.