Of course, in the older version (1.0.7) of Looter, turning on Loot by value and setting the gold/silver/copper to 0, would loot anything of value 0 copper or higher, which is effectively looting everything.

As of version 1.0.8, setting those values to 0 will literally loot everything.

In either case that will loot everything, and can easily be changed (setting a different value to loot by, or simply turning off loot by value) for when you want selective looting like in a dungeon run or some such, or loot everything without having to disable or turn off Looter via the checkbox.

Now what is the difference? Some items, particularly quest items, and items not yet in the item price mods tables (such as WoTLK items) have no value at all, not even 0 copper, and in 1.0.7 those items wouldn't loot (they would if they fit other looting settings like custom loot list, in the users quest item loot list, etc..) but not if it was a random item that dropped with no value at all (some fished crates/chests), but as of 1.0.8 and newer, they will.