She picked up something cold and super dark after focusing on Naruto up close for a while. Didn't however go immediately all 'oh its a bijuu up in hur'.
To someone who has no idea what they were looking for to start with, yes Dark and cold wouldn't scream Biju, but to Yujo who had the three tails for a significant amount of time would in fact know what that feeling was.
And she has negative emotion sensing now?
I agree with Warren. That doesn't mean she can sense bijuu. Remember that the Nine-Tails is malevolent by nature. I'm sure if she was focusing on Bee, she would not pick up something like that with the Eight-Tails. That happened way before Naruto & Kyuubi got along.
I dont think that's not negative emotion sensing. That's just the nature of Nine-Tails chakra.
Like how she said Naruto's chakra is warm and bright.
I addressed both of these issues.
Yes Mind's Eye CAN sense bijuu chakra. It's debatable if it is just kyuubi's. (Since he's evil) or if all bijuu have negative chakra.
No, it can't. Karin had to FOCUS on Naruto just to sense some malevolent chakra.
Using that logic, then Sasuke must be a jinchuuriki then since his chakra was evil. >.>
Malevolent chakra ≠ bijuu chakra
And even if you want to debate that, it still doesnt change the fact that Karin has to meet/see the person first.