We had a lumpia sale the other day, it was cooked by a volunteer to help raise money for a local charity. We had a 5 year old come in with, who knows what all over his hands and just grab handfulls of the lumpia out of a pan, take bites, and then throw it back.
Of course mom shook the lumpia out of his hand and appologized, she then picked three pieces from a different pan (they are three for a dollar) and then came to see me at the cash box.
I am still smiling when I think about asking her for $33.00, she instantly choked and demanded to know why I would charge her this much. I let her know that her child just ruined 100 pieces of Lumpia, and it's not fit to be sold, so i'm charging her. The instant response was, that she shouldn't be held responsible, kids will be kids, but I wouldn't relent, and she was forced to pay for it.
Which is what should happen in stores. If those grubby hands go in the candy container, make the parent pay for the whole tub. If they go into the popcorn, charge them for the bin (whether it's given away free or not, just for the inconvience of having to make more). Parents shouldn't be allowing their kids to pull stunts like this.