In several of the pictures I've seen recently, Koishi has been a bit of a troll and....apparently, not that bright...is it canon for her to be such a ditz? I should read more doujins and touhouwiki...
Had to think about this for a while. If anyone is misunderstanding my first post, its a response to if Koishi was a ditz in canon. Which she is not, I however stated who was actually indeed a ditz in canon confirmed by "word of god".