Talking of joss-sticks, when I was at college we had a tutor who absolutely hated the whole late 1960's flower power "scene" so we used to light two joss-sticks and hide them behind two radiators. One was near his desk so he could easily find it and get rid, thinking the pong would go, the other one he didn't know about, he thought the lingering odour was from the first, it drove him mad, he never cottoned on.
Serve him right. His idea of tutoring a lesson was to tell us students to copy out page after page from electrical engineering textbooks, about as fascinating as it sounds.