I was using the word cache loosely - forgot there's still places where folks may churn up the ground to bury a real cache. Out here in the PNW we try not to disturb the soil, instead you throw a trailhead bike or pack or non-essentials behind trees or ferns or rocks and usually return to find it okay. There's lots of cover ten feet off trail without burying things. And if its a food cache, much better to hang it than to bury it, today's cache hole becomes tomorrow's mud hole (once you've returned and emptied it out).

Someone else said something that strikes me as a good idea for marking gear so others don't assume its lost (besides a note) - put a rock on top of it. I can't think of too many situations when a thinking man won't ponder how that rock got there if the owner didn't place it.