Rule 5: "Note that age is based solely on visual appearance."

I feel like this clause of the rule is vaguely phrased. What exactly defines “looking old enough”? I’ve seen porn of canonically underage characters here (usually from Sonic the Hedgehog) that haven’t been removed by mods, and some of them didn’t make much effort to age them up visually.

@Anonymous #8BD8  
For most things, the litmus test is “if I showed this to someone that’s never seen furry art, the source material, or any sort of cartoons, would they think the character is underage?”