It has a very distinct smell. If you've encountered it then you know what I'm talking about. The smell really bothers me, more than feces, death, and all kinds of gross things. It might be the thought of what is actually happening to the flesh. Like those poor people are living with zombie toes, or whatever, attached to their bodies. I bet that's what zombies smell like.
Sometimes I'm reminded of the smell of gangrene for seemingly no reason, and then I'll feel a little ill.