1) Total mastery of the language of the original
2) Total mastery of the language of the translation, and
3) Total mastery of the subject matter of the work being translated.
The same criteria could easily be applied to academics, generally, and Jewish Studies, in particular. One must be thoroughly fluent in the languages of one's sources and in the subject matter. Since the language in which one is writing mediates between the sources and the reader, then absolute precision in translating concepts, modes of thought and sources is so critical as to be obvious.
Unfortunately, in many places, it is not obvious. Now, shoddy scholarship is not limited to any one group, or to any geographic location. It happens in Israel, as much as the Diaspora. ( Film historian, Shlomo Zand's obscene excuse for historiography is a recent case in point among Israelis. Zand embodies the exact opposite of Ibn Tibbon's sober assertion. He doesn't understand his sources and he isn't trained.)
However, as an American trained historian, it pains me to see that the most egregious situation is to be found in North America (and, to a lesser extent, Europe). It's not just a question of individual writers. As time goes on, the problem becomes increasingly structural (justifying manuscript boy's bottom line).
Briefly put, far too many PhD's in Post-Biblical Judaism and Jewish History lack basic Jewish literacy both in languages and Jewish Literature (broadly conceived). The result is nothing less than tragic. Some simply produce shoddy, 8th rate studies that may show awareness of other fields, but which scream ignorance of the sources that they are, prima facie, explaining. (I recently came upon a published paper on liturgy by a professor of Jewish Studies who didn't know the difference between חצי קדיש and קדיש תתקבל. Similarly, a study of Nachmanides was recently issued that was so egregious that a reviewer had to really stretch in order to find something positive to day about it. In other words, the number of academics to whom Haym Soloveitchik's strong words of protest apply is ever increasing. These, then become the mentors of the next generation, with all too foreseeable results.
Alternatively, aware of their deficiencies (or, being simply uninterested in the more substantive areas of Jewish Studies) scholars of Judaica opt to teach and undertake research in which Jewish literacy is less of an obstacle. In such cases, students are instilled with a less than total, or balanced, view of what Jewish civilization and experience comprehends.
Now, there are wonderful, brilliant, creative, responsible and broadly read scholars of Jewish Studies in the Diaspora. Many could teach the Israelis a thing or two about scholarship, and how to go about it (e.g. here, here, and here). Over all, though, the American scene appears (increasingly) to be the mirror-image of its Israeli counterpart. Thus, the Israeli foundation is sound, while the superstructure is weak (if one ever gets to building beyond the foundation). Abroad, elaborate buildings are constructed on severly compromised foundations.
The weight of the future, therefore, lies in teaching Israeli-trained scholars to build, and to build with vision. After all, כי מציון תצא תורה.