I came across something on why high IQ people (at least the one's we notice) seem so lacking in common sense.
...it has often been observed that high IQ types are lacking in ‘common sense’ – and especially when it comes to dealing with other human beings. General intelligence is not just a cognitive ability; it is also a cognitive disposition. So, the greater cognitive abilities of higher IQ tend also to be accompanied by a distinctive high IQ personality type...One must also keep in mind that "common sense" is why we have to teach people to fly airplanes. The word in that realm is: Trust your instruments Luke. Of course the instruments can give you a false picture. Just as your common sense can. The most useful rule is: