yankee:
I have never understood why a pretty girl would want to be spanked. I have always dreamed about it. <snip> I still love watching beautiful women spanked.
Well, weren't most beautiful women at an earlier point in their lives pretty girls?
Presumably, an underage female would wish to be spanked for the same basic reasons that an adult one would, the most obvious motivation being for erotic/playful purposes.
Of course, a girl wouldn't have to "want" a spanking to receive one, if she were subject to the corporally punitive authority of someone older than herself. Outside of the female having spanko-submissive desires and therefore consenting to her 'discipline,' it strikes me that it's easier for a writer to create a fairly realistic scenario within which an underage girl gets her bottom blistered, as opposed to a situation in which an adult woman does.
Not that it's impossible in either case, however it does seem less challenging with a thirteen-year-old feminine spankee rather than a thirty-year-old one...
--C.K.