At Mu Ying's current level, Slaughter Experience had completely disappeared, relying entirely on Professional Experience.
Aside from planting, caring for, and cultivating plants, and experiencing the animal forms of Wild Transformation, occasionally dealing with certain specific creatures or facilities also yielded Professional Experience.
With the Eye of Nature, she could identify the aura on them.
Not all creatures despised by nature could provide Druids with Professional Experience, but those that could provide Druids with Professional Experience were definitely despised by nature, and they certainly carried plenty of dark aura.
For instance, Blood Crows and Ghouls had plenty of dark aura, but they didn't cause much environmental damage, so killing them yielded no Professional Experience.
However, Withered Monsters also bore the black aura despised by nature but because they destroyed forest environments, killing them awarded Professional Experience.