Ah yes, I remember that one well. When I'd ask folks on my trip to said-country "
how do you know?" or "
what makes you think a treasure is somewhere here ?" (cave, ruin, floors, walls, yards, etc...), they would say "because someone saw smoke (or vapor, or lights, etc...) coming out of the ground. Other times it was because someone had a vision or dream. Or saw sparkles coming from the ground, etc...... Been there, done that.
Eventually, on our trip, I got to where I would outright reject any such reasons, and would not hike out to said places. And would tell them politely, "superstition". But no amount of attempt to explain this worked

They dug in their heels all more more, and simply became all the more convinced.
Like one time I hiked out to a small cave (alcove in a cliff is better description) where a man was convinced treasure was. After awhile, I finally asked "what makes you think so?". His answer was "sparkles" or something like that. There was absolutely nothing there. Totally sterile. Even in all metal maxed out. I even pulled out my headphone jack and let him listen, then compared that to the sound of the detector going over metal (my dig shovel, etc...) to show him it worked. Thinking "this will show him that there is nothing buried there". Ah but to no avail. He became convinced that the treasure, therefore, must be several feet deeper than the machine's ability to reach, hence needing a machine that goes several meters deep.
So you see, at NO TIME is it ever that a treasure isn't there. It's always just "deeper". And a few even told me that spirits move the treasures in the night, so that people can't find them (I'm not making this stuff up). So you can see why, after a week into it, I began to get very skeptical. But so too am I skeptical of treasure lore "dime store book type" treasure stuff here too.