This hasn't been my experience.
I have found that drunk people aren't as capable of concealing their true feelings or beliefs as sober people, such that people who are concealing those things to a significant degree are easier to understand when drunk... I agree with that much. But I've also found that drunk people aren't as capable of expressing their feelings or beliefs with any clarity as sober people, such that people whose feelings or beliefs are significantly complex are easier to understand when sober.
I suppose the tradeoff has to do with how much I value knowing the simple feelings/beliefs that my friends are concealing, vs how much I value knowing the complex feelings/beliefs they wish to express.
I've swung back and forth on this over the years, depending on who my friends are and what exactly is going on in my life, but in general I'm happiest when I'm focused on the latter.
The other day, someone did something I didn't expect. It was something many people have done before; something that I thought of as very normal, but that I in no way understood and had not predicted.
As I said, this had happened many time before, so I wrote it off as "me not understanding people" or "people are weird" for a second, like I usually do, before realizing that "bad at" really means "lacking basic knowledge", which I had never realized before.
And then I thought "I should ask someone who is different from me why people do that, and eventually someone will have an answer."
But many people will have many more questions like this. So, what have you observed people doing time and time again, but never understood? Or something that you only understood after a long time or asking someone about it?
And can Less Wrong tell us, not necessarily why (I for one can make up evolutionary psychology fairy tales all day if I want) but what conscious thought process occurs behind these events?