In a strong voice I would have pointed out to the staff that someone is sucking and chewing on the chips and the bags are now contaminated, perhaps they would like to move the display behind the counter.
It's an option (and not, necessarily, an incorrect one). But why be passive-aggressive about it? Just speak to the father instead of talking across him to someone else. I agree that moving the display might be needed. But you can mention that when you get to the cashier. Like another poster, though, I doubt they're going to remove the chips from the display. I suspect a lot more happens with things out in the public's grasp than we realize. Those chip bags weren't sterile before the little girl came in.
Like I said before, this situation doesn't have to be anywhere near as complex as some seem to be making it. Just tell the father that his daughter is doing something wrong. If he doesn't respond, take it further up the chain. But don't make this difficult - it's not!
As a paying customer I do not want to purchase something that has been in someone's mouth and chewed on. I don't think that is an unreasonable expectation. For me those chips are indeed contaminated and I don't want to buy them. I honestly don't know anyone who would be OK with it and I think the other people in line should know about it and then they can make their own choice as to whether to buy chips or not.
Oh, I'm not saying I want those bags, either. That's not an unreasonable expectation at all. I agree with you. My point was that we don't know what else has happened with the bags before that time - how many other kids may have chewed on them and not been noticed! If there are things out there where the public can touch them (or chew on them), you almost have to assume that the public has! Ideally, the chips would be in a place where they're not quite as easy to get to for kids to chew on like that. I'm assuming we're taking about Subway here. And the chips are quite accessible for anyone in line to touch.
You bolded the part about the bags not being sterile before the girl came in. And that's true. They weren't. If nothing else, everyone in this thread now knows that there are kids out there that do things like this (unfortunately). I think we'll all be a little more aware of it the next time we get a bag of chips at Subway - I know I'll get a bag from closer to the back myself from now on!
And I said that your option wasn't, necessarily, an incorrect one. I'm just saying that it is a more PA way to do it. If that's how you deal with a situation like this, go for it. Others may find that a more direct route works for them.