Why Do Some Farts Smell? (and Other Science Curiosities)

I've had several comments/questions regarding the title of this blog. If you are a student in my class right now or a former student, you know that we have class discussions about MANY gross topics regarding the human body. We actually spend one class period discussing the ins and outs of the large intestine, rectum, and anus.  With this discussion, we talk about why some farts are silent, some loud, why some smell, and some don't. This class is always a student favorite and one of mine as well.