I have had snake get bitten and scratched during live feeds - it takes a split second whether you are feeding responsibly or not - if you think it never happens you are deluding yourself.
Over the years I've gotten many snakes into my rescue that have lost tongues and eyes and have gotten sever infections due to untreated rodent bites. I had one that was turned over to the vet with a rat dangling out of it's mouth - it had bitten through the bottom of the snakes mouth during constriction - the owner didn't want to be bothered with the vet bill so decided to relinquish the animal instead. If you don't think it never happens you are deluding yourself.
I have paid good money to top breeders to receive snakes with obvious rodent scars - people post pictures on line of their beautiful snakes - they have obvious scars - what you think we don't notice them? People post pictures of their snake bites all the time - look under the "what is this?" posts.
If you think it never happens ....