I Have a *Name Has Been Changed For Privacy...

We'll say that her name is....Tammy*..that good?
Okay so I'm sure most of you have had one of these before, or at least seen it on TV. But this is my first one and I'm not entirely sure what to do or how to react, it is pretty funny though, hence numerous television shows based on these kind of people.
Tammy* is an older lady that I work with, and first I'd like to say that I personally have nothing against Tammy* this is just too funny and I am quite perplexed by the situation. She usually works at the cash wrap, she is insanely good at selling memberships, which is one of the things I am confused about...she'll sell like 20 in six hours. Everyone at Barnes and Noble really like her, everyone greets her with a smile and asks how she is, and it seems to be quite sincere when they do so. Everyone talks about her as though she was the coolest, nicest, saint of an old woman. They do extras and favors for her though she holds no high level job. She is bossy and even managers do what she asks, or rather tells. For me to tell you all these things that I see go on around me, you would think that she mush be the nicest, kindest, most loving, and respectful old lady in the world. That is not the case in this situation, and that is what sparks my interest and confusion. Tammy* has almost no facial expression unless you count the distaste that is permanently cemented on, her voice is low and monotone, she never smiles or is cheerful and when she does you think she might just deflate right in front of you, she is bossy and assumes that everyone knows less then her. So all these things are what I see and what I see confuses me. The way people treat her, is not the way that she acts, its as though I see the exact opposite that everyone else sees in her...
Like when she is talking to me and I want to turn around and run the other way screaming, running from the horrid monotone voice and the expressionless face, but I cant and I see a co-worker behind her pointing silently and mouthing, "I love her!". It scares me, it really does. It's almost a joke, the one person that you cant stand is every one's favorite and you don't know why. I would have to say that if I had to pick someone that I knew that was my exact opposite I would have to pick her.
It quite comical really.
And I realized this all today as she called me up to the cash wrap to further explain the same thing, that I might add I already knew, four times! And each time a manager was there to compliment her and thank her for taking her time to explain this remedial task to me.
oohhhh jeeez.

*name has been changed for privacy.