OMFG I do that all the time.....They are always like "would you like to buy some cookies sir" and I give them an appalled look and say "Sorry, I'm diabetic" Then I come out of Walmart with a box of Krispy Kremes and a blueberry/lemonade shush from the giant pretzle kiosk.
But I really hate the neighborhood kids when they are selling something at school......I don't even lie to them, I just say "look, you know damned well my kids are selling this same shit"
And I fucking miss Hastings.....So much awesome nerdy shit and books....How could they possibly close?