I’ve never created a character who is purely a sex worker, but with Guide I’ve come close.
1) Ruzhena is an information worker who sees sex as an optional add on to the contracts she hands out. She is ruthless and adds sex to blackmail and murder as tools to further her objectives.
2) Xeghita is an alien designed to seem human. She has developed a taste for men. Sex isn’t work for her; it’s more like a confection, which however few survive.
They have downsides to their characters, but realised that portraying both in a purely negative light was too simplistic.