How do you distinguish the “good” twin from the “evil” twin? Beards, moustaches and goatees all denote evil. It’s all about facial hair. Facial hair covers the face so it can mask the person themselves and their true maniacal intentions. When I think “evil twin”, I think about the parallel universe in Star Trek where evil Spock has a goatee. It’s been a long time since I saw that episode, but the “facial hair is evil” moral has stayed with me over the years.