What's the psyche behind greeting someone with "Is something wrong with you?"?

you can try a few different approaches, but the main thing to remember is that when someone is trying to push your buttons the one that loses his/her cool loses the arguement regardless of how well the points in the arguement is. I would go with "Why would anything be wrong with me?" or redirect the question in a polite way "No, but thanks for asking." or "No, is there anything wrong with you?" If all else fails use the broken record technique and say the same thing over maybe with a little twist and the other person will eventually get aggreviated or go away. Just don't let the other person bother you - I try to always smile and be polite. It is hard to hit a smiling target, lol.