
I do firmly believe that dogs ought be allowed to eat their meals in peace...
However, I also believe they should be taught to accept the occasional interference with food bowls because we humans are silly and will forget to add something, will walk past them... etc etc.
And it is my VERY strong belief that 99% of food bowl aggression issues are actually caused BY people repeatedly taking away food bowls or messing with them, to 'teach a dog who is boss'..
I teach my dogs using positive reward based training, so they already expect that interactions with me will be rewarding for them. I NEVER take away food bowls to do anything, preferring to add things to the bowl as it is on the floor or give the dog whatever ive forgotten later on after they have finished. I know I can take a food bowl off any of my dogs - but i dont need to do so, and i wouldnt teach a puppy to accept it by diving right in and snatching the food from them.
Instead with puppys if i walk past and i get growled at, i will monitor the issue - maybe its a one off, if it continues then ill make apoint of leaving an empty food bowl downa nd walking past it and dropping food in from a height (so that the dog is quite clear that food was dropped in - taking something away from a dog is a big deal and they care far more about 'you stole my....' than 'you gave me..' in that situation - just as i would be pretty peed off if someone snatched my purse, regardless of whether they then put a tenner in it and gave it back!)
If i have a dog that does have an issue around food then we work on that slowly, keeping it low pressure and crystal clear that people near food = good things. Never doing anything that can be misunderstood (so I wouldnt be putting hands in food bowls until the dog was happy with me standing near it, andi wouldnt stand near it until the dog was happy with me standing five feet away etc etc).
Unfortunately far too many people seem to think that takign something away and then giving it back teaches the dog to be good around food, even humans will react badly to having their plate snatched away mid meal, some will react surprisingly aggressively.
I once demonstrated this to a friend who was horrified and angry that her dog had 'dared' growl at her when she took a bone off her. Shed approached without warning and reached down and snatched the bone out of her dogs mouth and her dog had growled and snapped at her.
She sat on my sofa telling me how rude and nasty her dog had been, and started to eat her pizza.. so i waited until she had a slice half way to her mouth, leaned over without warning and snatched it out of her hand...
Well! She swore (v foul language) and actually raised her hand to hit me and then stopped herself and said 'oh!'... immediately realising my point (Shes used to mad behaviour from me).
If we humans will react by swearing and even body language suggesting physical violence... is it any surprise at ALL that a dog might react the same way!
Shes not done that to her dog since.. and ive not stolen any of her pizza since. (If anyone wants to try it, it really DOES bring home the level of outrage we feel and thus a dog feels at having something high value snatched away - dont try it with plated meals that involve pointy stabby forks and knives though. people get embarrassed at stabbing you in the hand with a fork!)