@ahltorp @acb @alice in my experience legal full service sex work vastly reduces the issue you lay out above.
When full service is fully legal and above board, people who want that simply go to where that's openly offered.
If they request an illegal on-the-side service in a non-brothel venue in a place where legal brothels exist (they still do, just less often), then they have no excuse. There's no plausible deniability in "well I thought this was a secret illegal brothel since brothels are illegal so I thought I was allowed to ask about sex". It's a very clear cut case of sexual harassment.