I've never really understood the harsh criticisms of MBTI. It's not super predictive, but not to be honest, nothing else in psychology is either; the whole field is just not anywhere near the level of physics or chemistry (not to blame the researchers; predicting humans is very hard). The big 5 and I think more recently an 18 dimensional breakdown (using PCA or ICA?) just aren't that much better than MBTI, despite ma…
Something I wonder is if people within different occupations tend to interpret the questions differently. That would explain a trend in the results, unrelated to personality.
There are also other types of ambiguity. For example when asking: "Do you keep your room in order?" - you might answer "yes" because that's what you do, but you only do it because it has been enforced into you over time, while if you were alone and free you'd keep it messy.
Do people respond with their instinctive reaction or with their trained reaction? Which one is the right answer? Depending on that you could get a different type.