I don't know if you folks are aware of it, but the emissivity changes according to the surface being read. A chrome surface (for instance) emits less inferred than a flat black surface. That's why a wood burning stove is usually flat black, and a pizza oven has a stainless steel door. Hence a chrome exhaust pipe will usually read lower with an inferred thermometer. A painted surface will probably read more accurately than a shiny surface.