Apparently there is a formula for the beer goggles effect.  How Stuff Works has put together a nice summary of what most experience but few truly understand.

Many of us have heard of the so-called “beer goggle” effect. It’s the phenomenon that occurs when someone’s had a few alcoholic drinks and suddenly, all of those people who looked semi-attractive on entering the bar look really, really appealing. Scientists have shown that it’s not just a lowering of standards — alcohol actually stimulates the part of the brain that judges facial attractiveness.

Read the full article here.