Taint add setbacks and debuf to characters in exchange for increased Experience and Loot. Also in Rotten Blood the more Taint the players will have a greater chance of looting the Rotten Heart and Darklight Heart that are needed to craft the Npc Altar. If you are in a party, the smallest Taint in the group will be counted as the basis for everyone.
It takes 05 Rotten Heart and 05 Darklight Heart + 50kk gold to exchange for a Bag You Covet which will randomly give you a Sanguine Item. In addition to this Hunt factor, you must have at least one Taint to have a chance to loot a Bag You Covet from any of the Rotten Blood bosses.