Lise--thanks for looking. I did see some photos of her in simple black thongs with a simple black slip dress. Context is everything--it was Tribeca, NYC, which is very dirty. You probably wouldn't do a whole day in those in that city, but she was coming out of a limo for an event there.
Often you see these shoes in laid-back, yet stylish environments, like strolling the farmers' market in Hollywood, or brunch with friends. They are a staple for many women, including myself. I would absolutely wear them with a maxi dress, because it is a good look.
The ones you would wear about town are usually silver, gold or black, though there are other colors. Flat and thin. You can wear them to the beach, too, but I would rather have a surf brand at the beach, like Roxy, which is a better look, and better in sand.