So Momma Doe licks the fawn all tidy-clean. If the result is less scent, does the cause really matter?
Well I guess that just really depends on whether or not you actually want to understand what is going on and if the information being passed onto is actually based on reality or not.
I would contend that when a set of circumstances is described to you that doesn't make much sense (pun intended), or the explanation for the circumstances doesn't make much sense, then there is probably good reason to question the validity of it.
There seems to be quite a bit of folklore associated with firearms, ballistics, terminal ballistics, and hunting. I don't see where passing on hokey information is beneficial to anyone.
I actually find the notion of fawns being virtually odorless as per TPWD to be rather interesting. Just because an animal is "virtually odorless" to humans doesn't mean it is virtually odorless to predators. Generally speaking, humans don't hunt by smell. The implication there is that if we can't smell it or smell it well, nothing else can, and that would likely be an incorrect statement since our capabilities are much less than those of many predators.
Above you also mentioned...
Wiping a fawn's butt with a warm, wet sponge triggers the nursing instinct, if you try to raise one. Baby bottles work well. Mix Carnation canned milk in a 1:3 ratio with water.
This activity is frowned upon by your friends at TPWD unless you first obtain the proper permits to do so. No person may legally be in possession of a live white-tailed deer in Texas without the proper permit from Texas Parks & Wildlife Department. Primarily, this is a Rehabilitator's Permit, Deer Breeder's Permit, or a Transfer Permit with an authorized Facility Id Number for Nursing or Veterinary Care...just in case anyone thought it might be fun to try.