

They generally have them on the containment units, and if they’re used elsewhere, on the pipes/machines carrying/using the chemicals.
Now, if they’ve been properly replaced since installation is a completely different question. I’ve seen far too many faded/shredded diamonds on the sides of things.
Some people find the experience of sticking things in their urethra highly stimulating. Some of those people get tired of the typical thin rod, and need something… More.
I’ve always been more curious as to who figured this out first. Someone had to be the first to scratch the inside of their dick with a stick to awaken a whole new itch, and I find that just slightly terrifying.