Do the Earth's poles ever suffer a reversal during a pole shift? No. The Earth's polarity, where the magnetic North Pole points consistently in one direction as though focused on a distant point in the Universe, does not change, ever. This is an illusion, a hypothesis that humans have concocted to explain what they find in the Earth's crust. In this hypothesis, they are assuming that the Earth's crust does not move about, but it does. What humans are measuring is the confusion in the crust, and not the direction of the magnetic North Pole. Between pole shifts, however, there are slight movements of the magnetic North Pole, especially during the time just before and after a pole shift - approximately a hundred years on either side. The giant comet speaks to the Earth from afar. Scientists who do not buy into the pole shift will argue endlessly that it is the poles that move and reverse, and any discussion with such scientists should begin by first clarifying the pole shift premise. Sometimes, during a pole shift, the movement is slight, and sometimes literal reversals take place, where the crust does, as you say, a 180. The coming shift will come close to that, being better than a quarter turn. Having only the Earth's crust to examine, and being in denial or unaware of pole shifts, a human could only assume that the poles had moved, rather than the crust.