Possible Clues:

• Bad person above all others joins up
• Patron of people writing with quill pens?
• Baddie offering liquid drug on street
• Notice clumsy worker being grabbed -- without hesitation, a nasty guy
• North American turtle that releases foul-smelling secretions
• Unwholesome character first joins in retreat
• Row better after turning turtle
• Despicable person
• Unpleasant (-smelling?) person