At my workplace, which sells some gourmet food items, we frequently set out samples, but almost all are set above a toddler's reach or in immediate visual range of the cashier. I've snatch the sample bowl or plate out of the reach of a roving child's grubby hand before he could make contact with the food, and tolerated the evil eye from the parent while handing her the tongs. I've also seen a child grab a cookie or other small pastry, and then put it back to grab another flavor or variety, while the mom is lunging for his hands. In those cases, Mom will grab tongs and napkin to pick up everything the kid has touched. I've listened to more than one conversation that went something like:
Kid: But I wanted to try the other one!
Mom: These cookies are for everyone. You didn't use the tongs and now you have eat what you touched.
Kid: Then can I try the other one?
Mom: No. You have your share. Eat your cookie.
I just wish conversations like that were more common, not just at my store's sample table, but at every store's sample table...