I don't think I do...you really made me stop and think for a while.
The grabbiness, though....
My guys are gentle when taking treats. At one point, one of the dog walkers we met frequently started carrying treats. She wouldn't allow the dogs to take the treat from her, though...she would toss the treat "last minute" toward their mouths. It showed my dogs that they needed to be excited and anticipate the throw...and they ended up snapping up the treats mid-air. Then they started anticipating other people's giving of treats to be the same way, even though that wasn't happening...but the dogs' were excitedly snapping up the treats. I had to reinforce "gentle" and asked the one woman to just stop giving them treats. I don't know if she just didn't want dog lips touching her hands or if she'd been used to grabby dogs. Her own dog wasn't grabby when I gave him treats myself.