Ethanol removes inhibitions, therefore people make bad decisions and they lose their filters which prevents their immoral impulses from rising to fruition. This is why someone being a "mean drunk" is a very bad sign...it's surfacing what is below the surface. If someone is a silly/happy drunk, it's a much more benign sign.
I don’t think most alcoholics would agree with this, btw. People who get drunk a lot usually aren’t one single emotion each time. This is almost on par with the belief that different liquors get you “different kinds” of drunk
