Interesting — I’d no idea that high humidity environments can do that. It seems that not all polymer & composite plastic shoe soles are created equal. I’ve seen some hold up horribly, while others are still going strong after 20 years, not even a sticky surface to them.
I wear flipflops around the house all the time. That’s a whole other topic—flipflop hygiene. If you have the kind with no center string, you can wear socks. But otherwise, the barefoot flipflops can get funky mighty quickly!
That’s the vexing thing about shoe makers. Sometimes they hit a mark of perfection and create a great shoe model, only to discontinue it some years later due to “style” or “management” changes. The Ecco Biom Grip II is such a shoe that suffered a recent discontinuation. One of the best casual shoes I’ve ever owned. So comfortable while having a cool look about them. Innovative tread too.