I think IQ tests are good for testing specific areas of intelligence. Like an employer testing in areas that are relevant to the job opening. But to say that one test can determine a person's entire intelligence capacity, probably isn't accurate. There are just too many areas, and variations, of the brain/intelligence to take into consideration, in order to create a accurate test. I think the only way to get an accurate measure of intelligence, would be to create custom tests engineered specifically for each individual, and this isn't practical, unless you are involved in something of great importance, like NASA, CIA, etc.... So, if you are interested in taking a totally accurate IQ test, be prepared, it would most likely be very expensive and time consuming, plus, I have no idea where you would go to have this done. I'm not even sure if they exist.
Us "pee-ons" must live with the general versions, which I agree, aren't very accurate. So, I guess we must live with the varied results, and just take them for worth they are worth. 
_________________
Those who speak, don't know.
Those who know, don't speak.