I have seen kids being carried out screaming and a few times have questioned if I should stop and ask the person if everything is alright. After all how easy to carry a very young nonverbal child out of the store as they scream and kick. Most people would simply think the kid was throwing a tantrum, right?
Boy, that is a tough one. I know I've carried mine out of the store screaming before, thinking I must look like an abusive mother. I remember seeing a preview for a family comedy (don't remember which one it was - only that it was on the BBC) and the father was trying to get the child to leave the store and the kid started yelling "stranger, stranger!" I thought it was funny at the time, but now I wonder.