I'm a newbie but I did some snooping around the site before I went searching & I came up with a list of things to keep in my backpack. I have extra ziplocks, extra logs, pencils, paper towels and wipes. And of course extra swag.
So far, we did have to wipe out a container and set up a makeshift ziplock cover because the lid was broken. I did post in my log about the lid just so the hider knows and may want to replace it.
If I ever come across a cache with garbage in it, I'll just toss it in the trash bag (Hmmmm maybe I should carry a pair of gloves too) and let the hider know in my log just in case this keeps happening and they may want to think about relocating.