My own rule is that I never do business with a JW unless it's a personal friend that I have complete confidence in and who just happens to be a Witness.
Of course, that situation doesn't arise very often. Those that know me are well aware that I no longer consider myself a JW. In fact, several in my family consider me a "dangerous apostate." Dangerous because I can out-reason the vast majority of them and know the Bible better than most. (Know as in "have knowledge of," as opposed to "belief in.")
Paradoxically (and thanks to Simon and this board), I often know more about the "current truth" they're supposed to believe now (after all the changes) and be ready to die for than they themselves do. More than once, when I mentioned something about the latest "new light," they scoffed and called it apostasy. The few who actually looked it up then claimed I misunderstood what they said. What they meant was...
Then it's, "Where did you get that information? It hadn't been released yet!" The source is more important than its accuracy. Go figure...
Sheesh! This forking cult is a festering boil on the butt of humanity. And so are all the others!