I think gold in general is a pretty ugly color, and its only value is its scarcity. Gold is always gaudy. I wish we would just use it for electronics where it is useful, but some people want to show off their wealth.
We are probably hard wired to think that white teeth are attractive, so it takes a major cultural phenomenon to overcome this and make a gold grill seem appealing.
Nevertheless, a fashion choice is a fashion choice. I see no reason to overreact.