And that's my point. You've had enough experiences to know better. I'd argue that others have as well. If you want to get wrapped around the word "universal" then how about "commonly-accepted"?

I am still amazed that people travel sockless and then complain when they have to remove their shoes at the checkpoint. Then again, this is nothing compared to the loose toothbrushes I see whenever I happen to check a toiletry bag. And don't get me started on women's cosmetics bags; talk about germ-city; and they apply this stuff on their faces?

Lots of people have dirty habits. Walking barefoot on a floor, unsanitary as it may be, pales in comparison to these other issues.

That's my point.