This potion is most useful when used with full screen and a high resolution. This way, it shows many more ores than it would otherwise be showing in windowed mode. This is more useful in jungle or corruption biomes, as they have more ores than others. However, many ores look the same; Copper Ore can be easily mistaken for Adamantite Ore. Hellstone is the only ore that is unaffected by Spelunker Potions, this is probably because Hellstone is always close to lava and is self-illuminated. This potion is very useful in the Underground Jungle, after hard-mode to mine Chlorophyte.
Notes
An easy way to distinguish Adamantite ore from Copper ore is the Adamantite's more violet appearance, as opposed to the Copper being more of a red.
It is recommended to use a Spelunker Potion and fly/grapple along the roof of the underworld to find any of the 3 hardmode ores, especially Adamantite/Titanium Ore, because they can be found in abundance at that depth.