WoW:API GetLootThreshold

Returns the currently active loot threshold as a number.

0 - Poor
1 - Common
2 - Uncommon
3 - Rare
4 - Epic
5 - Legendary
6 - Artifact

You can get the localized text for the loot quality from ITEM_QUALITYx_DESC.

/script message(getglobal("ITEM_QUALITY"..GetLootThreshold().."_DESC"))

The example above will show a message box of the current loot threshold.
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