I try to put my risk assessment in perspective. I worry most about things with the higher risk.

I leave my soap damp in an open mug in my basement. It is my soap and most of the germs if any are left there by myself. If they are deposited from the air of the house they are landing on my body anyway. Maybe my neighbor has MRSA and a mouse runs over his soap and then across the yard to my house and across my soap and if I cut myself while shaving the next day I might get infected.... Put it in perspective. I have more of a chance of many other things happening. I would fill up the server if I listed them all.

Concerning publicly shared soap even with liquid you usually have to put your hand on the pump to get the soap. That is pushed by the previous person with their "dirty" hands. What difference if they touch the pump or the bar?

At lest the people that use the soap are trying to keep clean. Then you go out with clean hands and touch the door knobs etc. that the people that didn't use soap touched.

Where is my bubble to live in? What if the bubble gets a leak and something leaks in that I have developed no immunity to gets in?

Where do I stop?

I work maintenance in a hospital and part of my job is unplugging toilets and drains. The stuff in the drains and any of the equipment I use are considered not hazardous!