In the study, microbiologist John Golobic, of Quest Diagnostics in New Mexico, swabbed a number of beards searching for bacteria.
Several beards contained normal bacteria, but some contained so much poo they were comparable to toilets, the results showed.
"Those are the types of things you'd find in (fecal matter)," Golobic said.
If there were similar samples in the water system, it would have to be shut down for disinfecting, said Golobic.
Golobic, however, said that the levels of uncleanliness were not enough to cause illness, 'metro.Co.Uk' reported.
"Try to keep your hands away from your face, as much as possible," he said.