Basic Trope: A sex worker who is kind-hearted, beautiful and attractive, usually to provide a romantic foil for the hero.
Straight: Alice is a beautiful, kind-hearted and innocent prostitute whom Bob falls in love with.
Exaggerated: Despite having worked the streets all her life, Alice is an All-Loving Hero who is worshipped and adored by all.
Downplayed: Alice is more innocent & kind than the rest of the cast, but still has moments where she's being mean.
Alice is a slightly naive innocent who has not been a prostitute for long.
Alice is a generally cheerful person, and her clients have been good to her thus far.
Alice, being as attractive as she is, has been able to charge a lot of money for her services & lives a life of luxury.
Where Alice lives, she can sue if someone tries to rape her while on the day and her employers have to pay for STD testing & the like. So she doesn't have to deal with a lot of the problems that come with prostitution.
Alice is a cold-hearted and cynical prostitute who exploits Bob's feelings for her own gain.
Or Bob is the kind-hearted sex-worker/male hooker that Alice falls in love with.
Or Bob is the client who is very much a Chivalrous Pervert, as against the expectation that he would be more likely to be just a not-so-chivalrous pervert.
Zig Zagged: Alice is nice to Bob one minute, slapping him around and calling him names the next, on top of going back and forth between diving unreservedly into selling her body and crying over it.
Alice is a multi-faceted individual, neither entirely a pure innocent nor a hardened cynic.
Alternatively, there just aren't any hookers as major characters.
Enforced: "It's pretty difficult to get an audience to sympathise with a woman in the sex industry; we'll have to make our sex worker character pretty and nice if we want people to like her."
Lampshaded: "To be honest, you're a lot nicer than I would have expected a woman in your line of work to be."
Alice intentionally cultivates an impression of being a sweet, kind-hearted woman in order to attract paying clients.
Or: Alice's pimp deliberately hires kind-hearted prostitutes because they're good for business.
Defied: Alice makes no secret of the fact that she's only after the money of the men who hire her, and that she doesn't like them at all.
Discussed: "You're looking for help down on Red Light Street, go see Alice; she may be a pro, but she's got a heart of gold, that girl."
Conversed: "I'm not sure the prostitutes in real life would be as nice as they are in these stories."
Deconstructed: Alice is only innocent and kind-hearted because she is naive when she enters the first life of a prostitute; however, years of being abused and exploited by men wear down her former idealism, she is raped several times which psychologically scars her, and she develops a crippling drug habit, all of which combine to reduce her to a cold-hearted cynic.