Yes, I believe that Tyrion's disastrous sex with the prostitute in Selhoris has been explicitely set up as a kind of turning point for Tyrion concerning his relations with women and the place sexuality has in his life. For the first time he is aware that paying for it will never get him what he wants. He is not the high lord anymore who can buy the disgust for the crippled dwarf out of the face of a sex worker, he has to take what he has paid for and that is a woman who does the least minimum to get the job done.
Actually it is a very typical for abused children later in life to be unable to distinguish between sex and genuine human interest. This may be the reason why Tyrion, given his normal perceptiveness, was so far quite unable to read the fake show prostitutes present to him, or at least manages to fool himself in a manner sufficient to him.
Although - I believe that here Tyrion is quite the average john. The emotional incompetence concerning his own sexuality is striking only in comparison to his competence, even emotional competence, in other fields.
If sex workers only sold their body they'd hardly meet the demands of their clients, or only of those with the barest minimum of coin. Not only abused men like Tyrion want to buy their specific story and illusion going along with the sexual services. Your friendly neighbour or the honorable major of your city does right the same, and so much more the average man in Westeros (of course not the Starks, they are the good guys IRONY) Prostitution does not sell sexual relief ( the men have hands, don't they?), it sells first of all a story, an illusion: the illusion of being desired, of being in power, of being in control (after your boss has just kicked your ass)......... whatever the man wants more of and cannot get enough in real life. And in Tyrion's case it is the illusion of being wanted, as man but as well as person, of being loved, something he is convinced he can never get again (I sooooo hope Martin will prove him wrong
) and a clever and successful sex worker will provide what clients want: the story behind. But the prostitute in Selhoris is beyond fulfilling a client's wish, she wants the job get done and does not care at all about putting up a show, thus confronting Tyrion very directly with his expectations in bought sex. And Tyrion is disgusted by himself he sees in this mirror.
Until then Tyrion is actually no worse or better than any other john and prostitution seems to be an everyday part of life in Martinworld.
Edited by Woman of War, 07 September 2012 - 09:03 AM.