i have found that during bondage sessions with my subs that i can always learn more about thier sexual desires when they are at the verge of orgasm. at these times i slow or stop just short of them orgasmming and ask them about thier sexual desires and not letting them orgasm till they have shared some deeper desire that they will not share openly at any other moment . then i work off of this desire on our next encounter. by taking little baby steps you can learn quite a lot .
i have also used porno movies during forplay and payed close attention to what was going on in the movie when my parter became totally arosed .One girl i dated was a total prude about women on women things but when we watched the pornos this was when she would become very excited and little by little she admitted that it was something she really desires but was ashamed of wantting . You could use this porno thing in reverce and let your parter see how excited you get dureing the acts you desire him to perform on you . when he sees that getting spanked really gets you hot he may feel freer to try this himself