Yeah, an oiran wasn’t some street corner crack whore, they were musicians/dancers/would recite poems and shit too. Plus they could turn down clients.
Yeah. She being a prostitute makes no sense to me because it was implied during her dialogue with Zoro that Komurasaki was a disguise and only a few people knows her true identity. So she was disguised as an Oiran and she was a Dayu, a Dayu only provides services to the Shogun and Daimyo. Currently in Wano there are no Daimyo in Orochi's reign, so unless people assume that she had sex with Orochi, she wasn't a prostitute. It's pretty obvious her wish to kill Orochi so it's unlikely she had sex with him... I'd say she was getting close to Orochi disguised as an Oiran in order to kill him.
But Oda did "that" for Viola's character and it came out of nowhere, now with Hiyori he has more "room" to do this kind of thing... I really hope he doesn't tho... Hiyori is basically being Zoro's girl I'd rather believe he wouldn't do something like that for Hiyori's character. Anyway regarding this matter I don't trust Oda.