Piss of course! "If you mix it with piss, it turns into candy. Delicious candy." +1 to anyone who gets the reference
In all seriousness, they probably taste like sugar water. If I was an alchemist, I'd carry around a bag of sugar and put some into whatever I made, since the components sound pretty foul. The actual liquid of the potion has to be water or something similar, since a lot of the components are dry and wouldn't create anything fluid.
If my alchemist was a Khajiit she'd probably use Moonsugar instead, because hilarity would ensue. I love the idea of potions progressively getting the character high by small degrees, that would be fun to roleplay.