Currently, Perky_Nipples defaults to Covered_Nipples. And while the nipples tend to be perky when they're covered. The same isn't said the other way around. Certain Imaged have the tag Covered_Nipples, when in reality, they're only Perky, and aren't Covered at all. I'll provide some examples:
All four of those imaged have Covered_Nipples in the tag, but they really mean Perky_Nipples since none of them are wearing tops of any kind. And they aren't the only ones like that. If Perky_Nipples could become it's own tag, it could clear up this confusion, and let people search for the tag of their liking in greater detail.