That's generally in cases where people have consented to*one specific sex act* with *one specific person* and have been deceived into participating in something quite different, though. Mostly it's to do with impersonating another, specific, person, as in the case of the identical twin who tricked his brother's girlfriend into sex, or like in the case of Assange where he was accused of deliberately removing a condom and continuing to have intercourse with a woman without asking if she was willing to have unprotected sex with him.

In the case of the Amazons, the sailors seem to be consenting to all the sexual stuff, but not consenting to the whole 'being murdered' thing.