Well I'm genuinely sorry if you feel that in the event of you being attacked it would somehow be your fault for not doing your advertising properly, but it's not only verbal or written language that make it clear somebody doesn't consent to having sex, especially if they're in the same room.
Plenty of punters over the years have turned up to be disappointed that a service they thought was on offer is not for all sorts of reasons, including misreading/misunderstanding an ad or more often just not reading it at all. The normal consequence of this is not that they assault or rape the person who is refusing consent unless they are rapists, and to suggest that if this happened it would be the responsibility of an advertising site being vague and therefore it's 'understandable' is beyond the pale - what on earth do you think people did before the internet? Or are you saying that you think non-British punters belong to some lower order and are not able to control themselves and their behaviour when told no?
Seriously, stop it. That is not a hint.