In relation to the second paragraph, I agree that it's not always a good idea to determine that a food item is done just by how it looks or smells. This isn't the case for all foods (such as cakes and pies), but meat is definitely the exception. Even if you do decide to cut it open on the inside and check the texture, it might look done, but there could still be some bacteria lurking about. This is especially the case with pork. Eating it undercooked will cause parasites, and no one wants that.