Answer:
I am always around you but often forgotten. I am pure and clean most of the time, but occasionally rotten. What am I?
Sometimes I annoy you, sometimes you can't live without me. But no matter how hard you try, you can't destroy me. What am I?
Use me to reward good behavior.
You use a knife to slice my head and weep beside me when I am dead.
I am a red drum which sounds without being touched, and grows silent, when touched. What am I?
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?