I have only been part of a clique once in my life, when I was in journo college in Chennai. For the first time in my life, I was among people I felt fully at home with. My friends tend to be few in number but close, and I am a different person in the company of close friends. It didn't feel like a clique then but years later a friend who was part of the clique told me one of her friends (who was not part of the clique) referred to us as the Mafia. All of us in the clique were smart, well-spoken and good at academics, (and the other males had a train of female admirers). We would also hang out a lot together so maybe a combination of all those things must have made us come across as snobbish. People behave differently when they are in groups. There is a different social dynamic at play, and someone you get along with well on an individual level might feel insufferable when in a group.
Since then, I have never been part of a clique or felt the desire. At my school in Holland, the cliques were mostly based on nationality, and since many of my classmates weren't fluent in English, that was understandable. There was one clique centered around an academic that would annoy me no end. Some of my good friends were a part of that clique.
Now, I am in a clique of one, but I am quite sensitive to their presence. I like to think I am good at sniffing out cliques, although it is possible I see cliques where there aren't any. There is a clique that I have identified consisting of grads from one particular "progressive" institute. Cliques in radical circles are even more annoying because the members sanctimoniously carp on about diversity and suchlike, while remaining ignorant of their own exclusionary behaviour. Maybe I am being to harsh. The line between a support network and a clique is a thin one. Unless there is tangible evidence of favouritism, it is difficult to accuse someone of being part of the clique. All one can do is be more conscious of one's behaviour when in a support network and try to encourage openness towards outsiders.