Are IQ test realy accurate?

Yes, they are. IQ tests 'test' logic. I took several exams. I have read a research saying that you cannot improve your IQ. You may raise your scores when you take the exam again -- but that is because you are already familiar with the exam.

Moreover, for IQ test reliability to be at its maximum, all unnecessary factors must be eliminated -- internal noises such as depression; external noises as well.

IQ test are usually solely based on how much you learnt from books and stuff like that and so I think they are not that accurate. If someone has a high IQ you usually think thier smart, but (and I know that soooo many people don't believe in this) what about someone with street smarts? These people know more about thier branch of life than anyone else, yet the most basic IQ test would rate most of them very low. Now, does that seem accurate to you?

The specific values in the discrete point system might not be of very use, except as a statistical benchmark for that specific test, so in fact it is the relative points (comparing results) that really counts.

However, many IQ tests are biased in some way (some are in English some are in Urdu; some put more weight into one kind of questions etc); but overall, they should work.

Note that intelligence, as measured by IQ tests, however, does not reflect the 'usefulness' of your brain. You are as useful as you make yourself; you can fail miserably on IQ tests, but still do much better in life's other aspects etc.

Not altogether. I have got different results for different tests. I think they are often based on language and mathematical skills, whereas you can have skills at other things. We all have areas of strength and areas of weakness. I personally tend to think we all get an equal drop - some are better socially, some intelletually, some emotionally etc. Just an opinion.

The test is reasonably accurate in itself. It's precisely WHAT it tests the is questionable. Someone with more reading experience, problem solving practice and general knowledge can get higher results. But someone how can build known facts to produce new knowledge may be considered more intelligent in a work situation.
A good memory shouldn't be confused with intelligence. Just ask Rainman.

It's hard to say, because there's nothing objective to measure them against. In any case I think it's accepted that the scores are approximate.