Actually a lot of the time they're not. They're not driven by gematriac agendas, they know the roots and semitic cognates better than most religious figures, and they're more honest about text gaps, additions, and pseudepigrapha than religious figures. Of course they're going to miss the mark sometimes like anyone, but it's easiest to be level when you don't have anything to defend.
And sometimes the texts are simply ambiguous and there's no way to know for sure, which is why you get such wild variations between translations.
Your mileage may, of course, vary.