The problem with having Obama take the test is that the test is known to be unreliable. Of course all paper and pencil tests have problems but it is widely recognized that the MBTI, even though it enjoys wide popularity, is exceptionally weak in test/re-test results. A person can take the MBTI several months apart and get very different results. The publishers of various tests boast about test-retest correlations between 70-90%. This would be considered “good” to “excellent.” But there is no way of knowing just how reliable a particular person’s ratings are without retaking the test. And if you do retake the test which score is the correct one? This means that there is a good chance that your health, attitude, anxiety level, amount of sleep, and/or personal problems will make your results inaccurate.
Look up the etymology or historical background of the word “personality”. It comes from the word “persona”, which refers to the mask that actors wore in the ancient theater. Too often, our personality is what we want people to think we are or what we want to imagine we are. So we are deceptive in our social interactions and we tend to lie in varying degrees on psychological tests.
Then there is the question of how well people understand the descriptive terms used on a test. What’s the difference between “anger” and “frustration?” Or is there a difference between being “careful” and “cautious” or “fearful” and “worried?” We don’t have a dictionary in our heads, let alone a thesaurus.
Are the various types real? What are we talking about? Are we really explaining personality or are we presenting a model of how words commonly used to describe personality are related. Some tests might even be considered word usage tests more than personality tests.
Even though the many psychological tests have problems, the dimensions seem to be accurate. The descriptions of the various types are fairly coherent. There is a real difference between INTP and ESFJ for example. But we need to make sure that we don't take what we think of as a "type" and get to using it as a prescription rather than a description.
It has been stated before it is hard to know another person's type with certainty. We routinely make that mistake in courtship. And some of the same factors enter in when we see a good looking smooth talking politician. We downplay their negatives and accent their possitives.