I agree that I think we all know more than we say we do when drunk and in a situation where we could say no or yes at the drop of a hat. The thing is that sometime alcohol gets us on a track that we realize is not right some how. Yet we can't figure out how, can't figure out how to get out of it so give up and keep on track even though we know that something isn't right. At least that is how I have experienced it.
I have been working super hard on that the last couple of years actually. I used to just say "fuck it" and do whatever anyway. Mostly putting myself in positions where I was used and disrespected yet everyone thought I was into what I was doing. It takes training, I think, to find ways to walk away from situations when we are drunk. Some of us aren't used to acknowledging sticky situations or know to train ourselves to walk away/say something. At least that is what I have noticed. I have noticed that having really clear boundaries helps. Although sometimes they aren't as clear as thought until something comes up. That doesn't make it okay, but it does give some indication of what needs to be worked on in the future.
For me its meant not getting that drunk with people I don't know the reputation of. I would never get that drunk in a group of BDSMers for instance, or with some sex positive groups. I know myself in the SOBER realm of these populations, and can think rationally. Drunk? Ya, I'm a crazy slut that does just about anything anyone suggests and even suggests stuff I wouldn't normally... The next day I am full of regret and for years after with some situations. Just not worth it.