Thank you all. I think the most important thing is to compare their interaction with the way they treat you daily. For example, does the person who talk to you standing close, ask if you need help with anything (a genuinely interested and caring person); or is she always asking you for excessive favors (a manipulator)?

And does that person stand close to you only when she is asking you for favors and distant other times? This is the case with the person I know. Everytime she asked to "hang out," it turned out she wanted something from me. Whenever she is around her nicely-dressed rich friends, she distances herself from me like she is ashamed of me or I am beneath her. But a sincerely caring person (and yes, I believe such people exist!) would stand close to me on a consistent basis, without wanting anything from me.