When in college I worked in a corporate biochemistry lab. My boss had a beef (pun) with the corporate cafeteria, so he had me take surface cultures from all sorts of different surfaces in the cafeteria— serving trays, dishes (ostensibly cleaned) chairs, floors, door handles, pretty much anywhere I could stick a contact dish.
The results were what WE expected, but absolutely scared the crap out of the staff.
We found most every ‘pathogen’ known to human kind (short of plague) growing somewhere in the cafeteria.
Serving trays were the most, ahem, bio-diverse. Floors were the cleanest, we think due to the biocides in the floor cleaners.
thankfully though our systems are mostly capable of fighting off infections- but every now and again, we get too much for our systems to handle, but it’s not really that common to do so-