Both times I ever wore them (yes both), puncture injuries to my feet occurred.
One an old rusted nail on the boardwalk at the Jersey beach, and the other was a piece of broken bottle ( also at the Jersey beach).
Well, when I think of beaches with heavy human presense, I think of all sorts of hardware in the sand. So, I would be wearing shoes there.
My experiences have been at beaches with no boardwalks, and very little human traffic. Even when visiting our son in Hawaii, we found a beach where swimming in water over chest deep was dangerous because of the rocks and waves. We had over a 1/4 mile of beach to ourselves.
Biting my tongue about even being near new Jersey
;-)