The Tur writes (113) says that if a non-Jew cooked meat without intending to cook, the meat's kosher and there's no issue of bishul akum.
An example that he gives is if a non-Jew singes the hair off a animal head and in the process fries the animal's ears, the ears are kosher.
However, the Tur finishes off saying that if the non-Jew lights an oven to dry vessels, but also knows that there's meat in the oven, the meat is forbidden as he might have had it in mind when lighting the fire.
How does this work with his example? He clearly saw the animal ears when removing the animal hair?