My original "Starfish" thongs were purchased in Denham, Western Australia [we live in Qld] simply because they looked like they would be comfortable. At one stage, subsequent to their purchase, I had problems with tendonitis for which I consulted a podiatrist who requested to see my footwear before making any recommendations.
He made some recommendations for changes in my shoes, but after turning my Starfish over and around to all angles, declared them to be suitable for me to wear. This gave me considerable assurance that not only were they comfortable, but they were good for my feet. I have been using them ever since.