How should we judge the trustworthiness of a given Bible translation?

Given that both the humans who actually penned the Bible and the later humans who translated it all had free will, the issue of Biblical inerrancy is a tricky one. See also: https://christianity.stackexchange.com/questions/3384/by-what-mechanism-could-the-bible-be-inerrant It is usually claimed that those transcribing and translating the text were working under the guidance of the Holy Spirit. While this may be true of some, it is also clear that not every translation project has even approached the work in good faith, much less under supernatural guidance. Some 'translations' are clearly contradictory with others, and others show obvious signs of a specific agenda being brought to the text. Others specifically state having a political bias going into the project (e.g. the Conservative Bible Project). Of course nearly every group or individual that produces a translation then goes on to claim that theirs is the "true" rendition of the text or meaning. Since clearly not _everyone_ that works on the Bible is guided by the Holy Spirit, **how are we to know which translations _are_ reliable?** Are modern and ancient mainstream translations considered to be free from political agendas and personal bias? If so, how do we know?