I'm not 100% sure that this is right, but I don't think wooden objects, for example, follow the law of reflection. If they did, then you would be able to see yourself when you looked down at your desk. I think, in that case, diffuse reflection occurs. Obviously, you have reflection - otherwise you wouldn't be able to see the desk, but diffuse reflection doesn't follow Snell's law. A physics student might be along in a minute to confirm if this is right or wrong.