Bad vibes

Anyone else ever get bad vibes about someone? My fiancé is trying to introduce an old friend of his back into our lives and something about her just puts me off. It's not because she's a girl, he has other girl friends, there's just something about her. It's the same vibe I got off another one of his "friends" and he now sees her as what she is and we don't associate with her very much. I got the vibe about her the second I met her and now I've got the same one with this girl. I did my best to make friends with the old one but I don't even know if I want to put in the effort this time around.