Sam hates the stigma attached to him, surrounding his job, moreso than most of the acts involved in the job. Like William, he has a lot of self-loathing that isn't necessary, that cultural hegemony has unloaded onto him. Howly did confirm to me that he loved having sex with clients since the beginning.
What Sam actually hates is struggling to scrape by with how little he's paid, and being demeaned for his reputation.
I don't think making a sex worker who loathes sex *itself* is necessarily a stronger narrative choice, or even a particularly unique one when it comes to how pop culture portrays sex workers vs. the frequent reality.
One of Sam's flaws is that he has good people in his life who he met through his sex work but is too bothered by the stigma to enjoy when good things are looking him in the face-- even if they're things that Sam loves.