As an MBTI presenter and administrator, I think it's great to help understand yourself and others. That said, "Anybody found one to be really useful in deciding whether to employ someone or to marry someone?" it is unethical (according the CPP the owner of the MBTI) to use it to screen potential employees (or I would add potential spouses....).
While MBTI career counseling is good to help understand what jobs you might like best, if someone is applying for a job, then they've already made a decision that they want to do it and it's not appropriate to screen based on YOUR judgement of the "right" type.
Stephen
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