Childermass can see why she might say that, to be fair, and he can't really argue that he isn't happier on a beach, surrounded by Growlithes, a drink in hand. It's a 'vacation', which is a concept he's never really had time to bother with until the carnival's more or less mandatory ones. Alola, the Summerlands, literally the moon...

Still, he feels the sensible need to point out, "These are so I don't stand out. Everyone else on these islands seems to wear them."

Or just, you know, actual colors. Of course, aside from Reira and himself, there are absolutely no other humans around, so it's not like he needs to be fitting in right this moment.