I think it is skewed to tell people what they want to hear. If I say, "I think EM is cool and sexy" then whenever I take the test, I am going to answer the questions accordingly like "I like quick care more than continuity," or "i like doing more than thinking." It may not give me EM as my number one, but it will give me a list of the "cool and sexy" specialties based on my current interest.
The problem lies with not knowing what you want in the first two or three years. I liked the idea of EM, but an anesthesia rotation my third year taught me how to apply physiology in medicine, and ever since then, I've known I have to go into a field with a lot of physiology application. In addition, my fourth year, I did some ICU rotations and realized that I want to have an more intense relationship with patients than a quick, "you aren't going to die." I am in peds now so as a direct example: seeing a kid, suturing his forehead, and sending him on his way is exponentially less important and satisfying to me than sitting down with a new ALL patient and their family and spending the time to answer all of their questions, help with all of their fears, and show them how we are going to do everything we can for them.
And I only say all of this because every specialty quiz i took said EM or something surgical, both of which I would hate to be in right now.