How do you know exactly what you have gotten sick from? Unless you can trace the source of the infection by matching it from blood samples to swabs around the room, you do not know if you have been sick from a hotel room or from someone coughing near you.

Viruses can be transmitted from surfaces to the skin, and then into your mucus membranes from rubbing your eyes, putting your hands in your mouth, picking your nose..and many of those are done without you knowing it. Remote controls, doorknobs, light switches..items that have a high interaction with human finger tips carry more pathogens than may be floating on dust or droplets in the air. 80% of the US population carries HSV1 although most don't develop symptoms..oral herpes...and it's not from sexual activity, it's from fever blisters on the lips that burst..the fluid carries the virus, and goes from there to the hands as people touch it and then the remote, doorknob. Then there is the adenovirus family, the norovirus, hepatitis, the rhino virus, influenza, about a billion unidentified viruses and the bacterial realm..ecoli, staph, strep,...and we cannot forget parasites..most transmitted from fluids on hands or on surfaces.

disgust is not an emotional construct, it is an evolutionary mechanism we developed over millions of years. If one member of the tribe was ill, those who felt aversion to that person survived to breed while those who did not went the way of the dodo. Those who stayed away from poo picked up less parasites and lived long enough to reproduce ..and today we have disgust for the same reasons.