Brosse6:
IMHO for a F/M spanking story to work well, the female has to be a credible dominant, which is why I think an image of a stern looking, less than attractive, mature matriarch is far more inspiring than some sexy young bimbo smiling and holding a cane.
As Eiffel points out the bondage stuff tends to get added, and I suspect that is because the female is actually not capable of topping without the restraints and fetish paraphernalia.
Spanking male scenes normally boil down to naught boy spanked by strict and mature Mom/Aunt/Teacher/Grandma/Neighbour's wife.
It's not at all impossible for a "sexy young" woman to be seriously spanko-dominant, however merely putting her in a black leather outfit while she's holding a whip won't make her that way--that's a simple albeit ineffective method of attempting to portray a basically 'vanilla' actress/model as a supposed dominatrix.
Beside which, I'm pretty certain that to spankophiles, the vast majority of F/M spanking accounts don't involve theatrically leather-clad, whip-wielding dominatrices.
However, there are certainly numerous women of various ages capable of soundly spanking men, of ANY age, demonstrating great control and self-confidence while doing so. Could greater age be a factor contributing to such dominance? Of course it could, yet that would apply to ALL spanking gender orientations--F/F, F/M, M/F & M/M--and it's hardly a necessary factor.
It's not difficult to find plenty of convincing F/M stories in this Library which feature younger or same-age females corporally correcting their menfolk.
To me, F/M spanking literature doesn't "normally boil down" to any particular age relationship between the spanker(s) and spankee(s), although of course any reader may personally prefer a specific type of age relationship in the F/M stories he/she reads...

--C.K.