There was a peer-reviewed report published in the journal for Applied and Environmental Microbiology that studied the amount of bacteria that was blown from hand dryers in 36 public restrooms at the University of Connecticut School of Medicine. The sample from the study concluded that as many as 60 colonies of bacteria were blown from a hand dryer in just 30-seconds. A number of those bacteria were linked to fecal and human bacteria, even bacteria known to cause serious infections.
Why YSK: So that you are informed for your own health, hygiene, and wellness and to prevent further spread of more harmful bacteria.
Citation & Sources: "Deposition of Bacteria and Bacterial Spores by Bathroom Hot-Air Hand Dryers" (April 2018), Applied and Environmental Microbiology
You should also know that when they test for fecal matter they aren't looking for actual pieces of poo they are looking for bacteria that are present in poo. You will find those bacteria just about everywhere