your kid is going behind your back then that's a parenting problem
Roger... not to offend either, but...
Consider this: My parents would scold me for wiping my mouth on my sleeves at dinner. My grandmother cut sleeves off my uncles old shirts an pulled them on as napkins.
Or let's look at it another way. I can solve the problem of my kid eating sweets before dinner in three ways
1. Leave a plate of cookies out on the table all day long and say "Don't eat those."
2. Lock up the plate of cookies completely out of sight and say "We'll have cookies only after dinner."
3. Have no cookies in the house and say "Sorry sweetie, we don't have any cookies."
4. Only have really, really crappy cookies.
To me, I as a kid, I would find it easiest and happiest to live in household number 3.
I added #4 because I realized that was my parents' strategy with TV - crappy little B&W tv with two clear channels. I noticed the kid next door with a big color TV and cable watched a lot more TV. Of course, if my mother had had her way, we would have watched a lot more too. The decision was economic.