This might be a bit off-topic because I was responding to the 'people who've had many sex partners' comment, and I've never been paid for sex. But since you asked:
Sex lost its intimacy and importance at that point in my life. I was looking for acceptance, intimacy and a sense of importance to men in general. I always equated sexual desire to power. It wasn't an intimate act shared between two people who want to show deep feelings of love, passion, etc. to one another. It was just a quick fuck, I felt fulfilled for a very short time afterwards (usually until the buzz wore off) and then felt like a complete piece of garbage. I thought that if a man chose to share his body with me, that surely it must be because I meant something .. When in reality it was the exact opposite. Most men that have casual sex with you care nothing about you. They're just tired of fucking their hand, simple as that. It took me a long time to understand and stop sleeping around with random men for an imaginary shot of power.
Thanks amiegrrl for your candor. I notice in myself that I can do the act but whether it is fulfilling or not depends on what is in my head about the other person. I mean the orgasm is the same, the physical sensations are the same but it's the mental connection which makes all the difference in the world on how satisfying the sex is. I think trust has a lot to do it for me. I don't think I could easily fake having satifying sex as a sex-worker - to fool yourself so to your own conceit.