RosieRad:
Like CrimsonKid, I like to play with semi-consensual adult scenes in my writing, and it's hard to come up with reasonable ways to do that, without veering into criminal or abusive situations. Fine line, and sometimes a cliche or two is needed
What works best, I'd venture, is basic reality.
When one adult administers a truly punitive butt-blistering to another one, what's the basis of that spanking discipline, if the person undergoing it genuinely doesn't desire to receive it and is obtaining no gratification (at least consciously) from his/her sound chastisement?
I'm figuring that, in the majority of such situations, the spankee has put his/her trust in the spanker's supposedly superior judgment and maturity, thus he/she has agreed to accept serious corporal correction from his/her disciplinarian, even on occasions in which he/she believes that it isn't deserved or required. This generally occurs within D/s and DD relationships (which may also include playful and/or erotic spankings), and to me is the most realistic portrayal of an adult consensually enduring corporal punishment which he/she really doesn't wish to undergo.
Sometimes such an arrangement might be codified by a written 'discipline contract,' which would be considered to be binding morally although of course not legally (some of my stories refer to such contracts), yet most often these understandings are apparently just a matter of verbal agreement.
However, occasionally it's fun to put a normally non-consenting adult into a situation in which he/she is forced to cooperate in receiving a good red-assed shellacking as the 'lesser of two evils,' which is presumably why punitive spanking blackmail shows up in quite a number of Library stories...

--C.K.