Plants smell nice in my opinion, valerian included. The concentrated root is a bit too much, yes, but it's far from being one of the worst. I love the smell of good cannabis. Datura and henbane have interesting smells, almost mystical in a way, but perhaps it's my imagination because I have a lot of respect for those plants.
I'm not much of a pill popper, but the worst I've come across is Sudafed's pseudoephedrine. Even the coating is quite unpleasantly tasting; once I tried chewing them, fuck me was that nasty. Pure alcohol tastes like ass in my opinion as well. Most nitrogen bases (alkaloids and synthetics) taste poorly in solution, although I quite like codeine's taste for some reason, and I seem to be the only person to do so among my friends who have done it with me.