Separating the issues of sex for money from the issues of slavery; A one on one consensual interaction between adults is really between the adults interacting.

A married man supporting a mistress in addition to his family.

A single man supporting a mistress.

A group of men supporting a single mistress.

A group of men supporting a network of lovers.

A group of men supporting a network of sex workers.

A single man paying a single woman for a date.

A single man paying a single woman for sex.

A single man paying many women for sex.

A married man paying a single woman for sex.

A married man paying many women for sex.

Who's the injured party in a primarily tort based system?

Wives if they exist and if they object or are injured.

If a mistress is not to be arrested, why should a prostitute be arrested.

This all assumes an uncoerced freely entered into relationship.