Can the term "insincere" be used, as opposed to "fake"? The latter reminds me oh so much of high school, and years before... But more to the point, I think a lot of the arguments made here are a bit too accusatory. Being insincere can just as easily be defensive as it can be offensive, especially in a situation in which someone is uncomfortable (and for a moment, lets got off the subject of how people act towards YOU, and consider,maybe, how you act towards THEM). And, if there is some kind of insincerity going on, I think an evaluation of it is necessary, as there does seem to be this divide between the offensive and defensive. If someone is being offensively insincere, then they obviously feel some kind of need to distance themselves from what you bring to the table, regardless of acquaintance. I think a lot of insults come under this distinction. But theres also a kind of protective insincerity, like not telling the whole story, that protects them from you're inquiries. Both can easily seem to be accosting in retrospection, but for the most part I don't think its some kind of habit that forms as distinct from one's own interaction with another. Insincerity can only happen in some kind of relationship, and like it or not, YOU are some part of that relationship, and so have a distinctly positive or negative influence over it.