I personally don't see any need to wipe my DS's tongue. Breast milk is completely natural, and it's what his body is designed to eat. It just doesn't make any sense to me that breast milk residue in his mouth would be so dangerous as to lead to infections. If that were the case, the human race would have died out long ago. Honestly, I think the wiping is MORE likely to cause infection than not wiping, because it likely causes small scrapes where bacteria can enter. And I would worry about causing DS to have an oral aversion from all the gagging and tongue scraping.