Personality tests administered and reviewed by any one other than trained professionals is vague at best. They are meant to be viewed as part of the process, not "yay or nay".
However, it is important to understand how they work. You do need to know that there are "cheat" questions through out. They are designed to see if you're lying or at least answering them as you "think" they needed to be answered.
A simple one is "are you always on time?" If you answer "yes" - then it is a strong marker that you're lying. Reason. You might be early.