Then again, as a psychologist said, if you're intelligent, you'll do well in everything, no matter how bad the test is.
That's the biggest load of bullshit I've ever heard; didn't we just discuss the modular and diverse nature of intelligence?
This is the interesting thing. IQ tests are basically "can you read my mind" tests. It's a horrible method. But... smart people will always find a way there.
Among some of the smartest people I know - CEOs, self-made tycoons, Harvard postgraduates, national advisors, modern inventors, freelancing hackers - all of them have the same thing in common. They work hard. They can think differently and are quite open minded; they don't run away when they see something they don't want to believe. This open mindedness could be that correlation between intelligence and insanity someone suggested earlier.
IQ tests worked at one time because there's no "expected solution". With a knowledge based test, anyone who knew/memorized the right answer has a huge advantage. But generally, smart people will figure out a way to get the answer no matter what. IQ tests are partly about perseverance too.
Stupid people would give up before looking. Think of the most stupid people you know. Chances are they never finished their homework. Lack of wisdom comes with lack of patience. The petty thief, the crack dealer, the knocked up teenager, gambler, /b/tard. They will score low IQs, because when they look at a IQ test, they go "wtf is this?"
You can have a horribly designed test, and a truly smart person will score at it. Some would score at 110, some at 130, 150, but it doesn't matter, they still score above average statistically. Heck, give a man a test on say, anthropology, geography, or Russian linguistics, and the smarter man will score higher than the dumb one, even if neither of them studied.
True story: My dad had to take a test in Japanese to get a scholarship (to Japan). No potential scholars knew Japanese. All, but two people left the room without answering anything. He and the other person took random guesses at it, basically just filling in their name, age, "yes/no". Both of them got the scholarship.
True story 2: A game development company has to find capable programmers, but none of the local colleges actually teach programming. Most colleges test their students entirely on their ability to memorize the textbooks and helpfiles, and many can't even answer questions from the first chapter of C++ for Dummies. The company decides to pick people by interview. The ones who became the best programmers (after training) were the ones with the highest grades. Even though the grading system was completely retarded.
tl;dr: IQ tests are badly designed, but an indicator. They're an inaccurate indicator of intelligence, but still an indicator.