I am rigorous about it when at home, especially since we have two dogs (one still a lick-obsessed pup) and a cat. Also if I have been handling food.
But, you know, real life often intrudes, when out and about.
In that situation, I lick my finger (checking for any sweetness), wipe in on a clean piece of clothing (say under a collar) and get on with testing. In those circs, I then lick the blood drop off too.
If I need to test, and I am not near a bathroom, then... I need to test, don't I?
For a while I carried those little individually wrapped wipes, but apart from the expense, I suspected that the cleaning agent residue was affecting the reading.