Almost there already - one kid came to the door last year and when I gave him a bag of chips he said "Don't you have anything better?"... so he got nothing. I can't believe there are parents that raise kids to be that entitled. Sadly the fun is rapidly disappearing and it is becoming nothing more than "gimme". 
It does go the other way though, the Halloween before last one little boy came to our door in the pouring rain (with his Dad) and I gave him his treat and he politely thanked me and turned away - he was such a good kid that I called him back and gave him a couple of fistfuls of chocolate bars.