When I burn in the insert, I don't get any odors - good or bad. With my insert (2 years old), there will occasionally be some smoke that comes out when I am reloading. But, I am pretty careful and so far have only burned a limited range of woods - oak, mulberry, locust and maple. Can't tell much difference among these woods, especially since I usually have a mixed load. One really notices a difference when smoking or barbecuing. In these tasks the smoke flavor is critical, and you have to pay very close attention to what you are using - grape vines, hickory, apple, cherry, etc..