Well, yeah,
My Masters thesis involved paleomagnetism, which is all about the constantly moving poles.
I have used a sun compass to collect orientation data on highly magnetized outcrops. Hell, I've had credits cards in my wallet lose their magnetic data because of sitting on magnetite rich rocks. And if you are in an active mine, there are often high voltage powerlines nearby (like right next to you, when you are ankle deep in water), which totally screw with a compass.