True. I was thinking in more absolute terms. Hitting a critter with Lightning is bad ("negative" ) for the critter, regardless of which player is controlling the critter. Since this can happen to both players' critters, I assumed that's what you meant.
I agree that applying PU to the target player's creatures is bad for the target player and good for the casting player. In addition, destroying the casting player's creatures is bad for the casting player and good for the target player. In the case of Pandemonium, the "goodness" or "badness" of a particular effect depends entirely on the side of the board on which you're sitting.