it blows my mind that people think that if they have someone coming over- paid or not - that you should have to consider whether you have to tell them they are walking into a space where someone else may be there or not: OF COURSE YOU SHOULD TELL THEM.
Jesus Christ!
if you walked into a providers house and there was someone else sitting there, unknown and unexpected to be there, you too would freak out or be unnerved, regardless of how sex positive they profess to be AFTER THE FACT.
have some basic decorum and manners. PLEASE.