For me, personality tests are like a piece of free candy, if I see one, I'll take it. They can be serious, like Myers Briggs, or fun, like the "what do you see" Rorschach-like personality tests constantly popping up on Facebook.
Why do we read scary books and sit in dark rooms watching horror movies? Are we just morons? Let's assume in general we're a smart species. If that's the case, what draws us to haunted houses and movies about ax murders? Why are writers like Stephen King and R. L. Stein so popular? I think to understand that, we need to take a lesson from psychology.