I've always avoided swimming because of this. Other people, who may not wipe their bottoms properly, are getting into the same pool as you. Sometimes they pee (and they always excrete saliva) into the pool. It kind of grosses me out, and I've never really understood why it's not more taboo.
In elementary school, I was never a fan of the game "bobbing for apples", because all of the other kids stick their mouths into the same bucket, and I had a basic conceptual understanding of germs and how they spread.
Not washing your hands 20 times a day or profusely applying hand sanitizer is something to avoid. Doesn't mean you should be seeking out bacteria, though.
In elementary school, I was never a fan of the game "bobbing for apples", because all of the other kids stick their mouths into the same bucket, and I had a basic conceptual understanding of germs and how they spread.