Dear joninliverton,
Thank you so much adding your perspective to the discussion.  I shared in much the same experience while growing up.  Consequently, I don't like or understand "violence for violence sake" with a world already overfilled with senseless violence!  
In my opinion, maybe the sensation of slapping someone hard enough on the ass to leave red marks conjurs up the momentary notion of "dominance", but so does "branding" with a "RED HOT Branding Iron " (like one uses on cattle).  I cannot imagine what positive good could possibly result for the victim of such abuse, but its initial goal is to "create an inequality between the two partners".  Then, if successful, it probably succeeds at the time for precisely the wrong reason and in the wrong direction, resulting in something other than a "viable and healthy relationship".  
Some people innocently enough quickly dismiss this as only being "role playing", but don't forget you are playing with real people; with real feelings; that have real limits.  Over time, these kinds of demands made on any relationship consistently has to run a higher than average chance of wearing thin, just when one takes the other partner "a little too much for granted some eventful day".  Then, it is too late to save it!  Its like playing an mind game of Russian Roulette"!  I have to ask myself..."Why chance the consequences with someone you really love"?
Sincerely,
Stimpy