Noise is the answer. 3D programs today can render perfect object easily. But perfect object have a plastic fake quality to them. Think of the first Toy Story vs Final Fantasy. So a perfect metal need noise like rust, poc marks, scratches and smudges to have a more realistic feel. Although the pool ball are well rendered they're too perfect Real pool ball have subtle flaws on the surface that lend it self to appearing more realistic. The most realistic pictures I've seen with Vue have noise or distortion of the surface. And of course a good mesh helps.