Most Helpful Guy
I think alcohol is truth serum up to a certain point, in which the person who drinks still can be logical and insightful. The right amount gets your guard down but makes you speak more truthfully and reveal more about oneself. Confidence also comes with drinking because it gets rid of the anxiety and awkwardness with whomever you're drinking with. So, alcohol taps into both honesty and confidence. Once you get past a certain point, that's when people just become stupid drunk. However, even in the midst of being super drunk, they will subconsciously speak the truth about whatever is on their minds, whether they remember it or not the next day.
Most Helpful Girl
It can be. Based on my observations of people around me when they get drunk, they tend to say the things that they are suppressing inside, and to say them out is a sort of relief for them. It makes them forget about their stress and problems for a while, and mostly to rant. This is probably why some people like to get drunk.