While we need to not be obsessive about cleanliness - our immune systems need some stimulus - use it or lose it, we also need to look after ourselves and attempt to not share too many bugs.
Yeah, I don't see this as a complicated or difficult issue. To me it is simply common courtesy. I don't particularly care if someone has poor hygiene habits in their home or with their family. Whatever. However, the moment they step into the dojo it becomes everyone's concern.
Wash the damned gi...
I worked for a few years when I was in college sterilizing medical instruments. The stuff I read and learned while doing that forever convinced me of the absolute power of a little water, soap, and rubbing. Some bad bugs are really hard to kill once they get entrenched. But those same things are so easily prevented most of the time by simply keeping everything reasonably clean. An ounce of prevention...