At first I really didn't like the idea of rape by deception. It seems like a dangerous slippery slope. I decided that a solid legal standard would be if the perpetrator tells a lie that s/he knows or should know will be a critical factor in the granting of consent. That's a fairly high standard, but we're talking about criminal law, if anything it felt potentially too low. We laugh at characters like Barney on How I Met Your Mother, when he lies his way into a girl's bedroom. Do we want to send him to jail?
Upon further consideration I've realized this is an odd social programming. There is a crime called 'larceny by trick.' If I lie to you in order to convince you to give me your stuff, I've committed a crime. If I lie to you to get you to consent to sexual activity, no crime. Shouldn't our sexually repressed culture be more concerned about chastity than things? I think I'll have to reconsider what is a fairly patriarchal view that boys lying and tricking their way to sex is just boys being boys.