People assume that those with facial hair are more likely to harbour bacteria on their faces than the clean-shaven – but the truth is more tangled The idea that beards are dirtier than clean-shaven faces has been floating around for decades, says John Tregoning, professor of vaccine immunology at Imperial College London. There is even research that shows people perceive bearded men as less hygienic: one study found restaurant customers rated waiters with facial hair as dirtier. Science doesn’t n