Noisome means having a bad odor or being foul smelling. The word also describes something that is harmful to your health, vulgar, or toxic — just plain nasty.
In War and Peace, Prince Andrew is severely wounded, and his flesh is putrefying:
The doctor and valet lifted the cloak with which he was covered and, making wry faces at the noisome smell of mortifying flesh that came from the wound, began examining that dreadful place. The doctor was very much displeased about something and made a change in the dressings . . .