They aren't even bad. What is missing is a physical(call it somatic if you will) component. There are two things which are important in MBTI or Socio or wherever:
1. How you react
2. What you say/choose
Do notice the order! I haven't put it like that just because! Corollary to this is:
Without the most important part...how are we supposed to know if a person is cognitive biasing it or if he really means what he chooses. Two more things:
The tests are almost always so definite. You like to be alone: Y/N . Wtf? There are times when I do and times when I don't. I mostly do, but that's besides the point. I as a representative of mostly, a person who is a represntative of alone = better than in a group, both = good and a person that prefers monastic life get the same amount of points! WTF!
I'd say that most of these tests reflect our likes/dislikes NOT our COGNITION! Cognition != (dis)like ! What this means is that these tests, more often than not, give us a result that better describes our perfect mate(be it a friend, coworker or, well, sexual mate) than it does in describing us. Just think about it!