I think that won't affect the perfume? He didn't perfume in the hand, to begin with. He did it in his upper body like shoulder, chest, arm, or neck. If he only did on his hand then, his identity was already identified when someone gets near to him.
           Just imagine if you use perfume and let's just say the odor of ours is the human smell. (Cuz monsters had a sense of smell)
          You spray in the neck area. You should put some perfume to blend the odor or use some more to vanish the human odor. It all depends on how much amount you spray. (Sorry kinda mess my words. Not good at English)