Hmm. I don't know so much about this. It's usually easiest for me to spot extroverted types - ESFJs, ESFPs, ESTPs, ENFJs, etc...because their personality is more out there. I also think I know an INTJ when I see one.
With NF women especially I feel a certain connection of being understood, and learning about MBTI helped me to get what that was.
But no, I don't see NFs by the look in their eye.