Two things I have found with all my non-stick pots and pans:
1. There is always more oil in the center because the center always gets dished. I think this is because the center is much hotter and the metal expands. Yet the outside ring of metal restricts expansion because the metal is colder. It's like a bottle with 3 inch thick wall. The center in time gets deformed into dish shaped.
2. The center becomes non-stick because high heat eventually destroys the non-stick coating material.
Regarding wine glass "legs". It may also be that many people wash their wine glasses separately and not in the dishwasher. The dish washing detergent generally has "sheeting" chemicals which allows water to drain down faster.
dcarch
