1. The surface of the oil cup is clean and free of debris
2. There are no signs of bumps or cracks on the surface of the oil cup.
3. There are no bubbles or pits left on the inner surface of the oil cup due to manufacturing processes.
4. There are no obvious bubbles (within 2mm in diameter) or a series of bubble groups inside the oil cup glass.
5. There are no obvious scratches on the surface of the oil cup.
6. The oil cup has no oil leakage.
