After my kids began insisting that I kiss the EXACT plan where the boo boo is, I create a new strategy - I kissed my hand, then gave them the kiss. They took it and put it on the boo boo, and all was well :) I would even give them extras to put in their pocket, and if I was too far away/occupied they would take the kiss out of their pocket and apply it to the boo boo for instant comfort :) I guess the saliva effect didn't really come into play here but the psychological aspect worked beautifully!