Its the most generic explanation I can use in the shortest amount of text that generally gets the point across. It is a lousy example. It's obvious when people are smart/intelligent and also obvious when the are not, I believe its largely genetic and out of people's control so discussing it or creating websites to better your 'IQ' are mostly a waste of time.
I don't think it's obvious at all, and I think people often mistake a number of other things in others (philosophical agreement, expertise in a domain, certain social skills, among others) for general intelligence.
There's also considerable evidence, IIRC, that, while the upper limit a person can reach in intelligence is genetic, that environmental factors play significant roles in both how closely that limit will ever be approached and how well/long what is achieved will be maintained.
Well we'll just agree to disagree on this one :) At the end of the day though it doesn't matter if either one of us is correct, nothing really changes either way.
