<span style="color:green;">I noticed this with the "Hidden Treasure" Magic Item. While in the ruins, search for the Hidden Treasure with the radar as usual. Once finished, talk with Quigley (the mole kid), and the hidden treasure respawns each time in the location it was hidden. This does work when speaking with other characters as well, though it doesn't work with all of them, and it always works with the kid. You can collect cash even faster if the chest is hidden where Quigley is normally floating around. Just collect, chat, collect, chat...wash, rinse and repeat.
Note: I was at the very end of the game when I found this. I'm not 100% sure it works at prior points in the game, but its very likely that it does.</span>