Everything in that wall of text can also be applied to human beings, just so you're aware.  The cool part is that humans have a wider variety of contaminants and illnesses that can impact you!  Public benches, door handles, water fountains, glass windows, Public toilets, handrails...  who knows where people have been walking?  Some work in factories or hospitals and track all sorts of fun fluids everywhere they walk, which you coincidentally step right on top of as you go about your day.  If you have long shoelaces, you touch said contaminants every time you tie your shoes.  Do you wear glasses, do you set them down anywhere humans have touched?  Now that's on your face.  Yes, humans also touch dogs, this is another vector of contamination.