I tape wirenuts, which I attribute to my begginings as a machine electrician. It was a requirement where I worked. The accepted feeling was that without tape, vibration would loosen the nut.
I recommend tape where there's vibration (dishwasher, furnace, vent fans, ceiling fans, etc.) and also for emergrency circuits, where a loosened connection would be more than an inconvenience. In the end I tape them all rather than thinking about it.
However, I use a method that makes it easier to untape the wirenut, which I think is the real issue about taping.
Dave
