I saw a father on a hiking trip with his young son teaching his son to clean a knife's blade by pinching the blade with his thumb and index finger from the edge side of the blade and drawing the sharp edge lengthwise between his thumb and finger.
I about had apoplexy. We were at least 2 hours from any transport or medical assistance. I politely suggested that if one is going to use one's fingers to clear off a blade one should instead wipe the blade on one's jeans from back side to edge, pulling away from the edge.
I was loudly told to f*** off.