I went to Kiyomizudera a couple years ago on a really busy day (mind you, it's always sort of busy there). That main deck there was extremely smokey with incense, far more than I'm ever used to. My jacket smelled for days, more like charcoal than insense. Like jib said, not all temples are alike. But if you go to a really busy one and smell trouble, just stay away from the smoke.