There are quite a few base potions in the game's code that were left with no method to craft them in 1.9 beta pre-release 3. These potions include: Clear, Diffuse, Artless, Thin, Bungling, Suave, Smooth, Debonair, Charming, Refined, Cordial, Sparkling, Potent, Rank, Acrid, Gross, and Stinky.

While they can still be obtained using commands, they have no effect, and take the appearance of a water bottle.
Contributed by frankfrost2