"lol Yes, any time a woman has sex while drunk, she is being raped."

I tend to find the problem with these discussions are that people use the term 'drunk' differently, which isn't surprising as there is no cut-off point between 'no drunk' and 'drunk'

This is why I went for 'as drunk as possible whilst still being able to express willingness to have sex': "How about if they're too intoxicated to stand, remember what they were doing half a minute ago, but are just about able to slur our the word 'yes'?"

Let's fill out that scenario a bit more; you go to a party. At this party there is a long-term couple, they've been together most of their lives. The woman is someone you know and have fancied, but she's never been interested in you. The couple are drinking, and have a huge earth-shaking fight and she's very upset and continues drinking. She over-does it and drinks to excess, to the point of being barely able to talk.

She's very emotionally vulnerable, she's impaired through alcohol, and wants to have sex with you as a revenge fuck, which will undoubtedly make her feel sick, disgusted and ashamed of herself in the morning.

She's saying 'yes', but is it ethical to have sex with her?

Sleeping with her rather seems like vile behaviour to me. It would seem to be obviously callous behaviour.