The trio interviewed a long list of students visiting a local pub near the university and did a series of tests by showing them photos of people to see if they could tell the images had been altered to make them less symmetrical.
Symmetry is considered to be an important aspect of what makes a person beautiful. After dividing the people into two groups (drunk vs non-drunk) using a breathalyzer they determined that drunk people are unable to differentiate assymetry.
Thus "Beer Goggles" really does make people around you look more attractive, at least as far as your brain is concerned.
Tracking the results the researchers also discovered women are more prone to losing their sense of assymetry. Not because they get drunk easier, oh no, its because men pay more attention to appearance... or more precisely, men leer at women and are checking out their breasts/etc in detail.
In which case leering may actually be an evolutionary skill designed to pick out women which are more symmetrical and healthy looking. Whoddathunkit?