Has your lizard ever gotten things stuck on his tail without realizing it?
Sunesu's tail is muscular and powerful, but most of the protrusions are in fact fins similar to betta fishes and the like. They're pretty fragile and tear easily, but grow back similarly quickly. So it is less things sticking to it, and it sticking to other things without him realizing. After reaching more populous areas like Kugane or later Eorzea however, he quickly became quite self-aware of it in crowds and does his best to avoid incidental contact.
(yes hello you stumbled on OC anatomy lore, congratulations!)