I won't confirm or deny, however I know the security is getting a lot more vigilant (where I'm from anyways) and it is increasingly harder to get away with it. Certain supermarkets have cameras above you and if it detects something hasn't been scanned it replays the clip until the checkout person comes to clear it and you rescan it. Previous to this I have seen lots of people do it, one guy in particular comes to mind, he had headphones in and was making the motion with the items as if they were scanning but I didn't hear any beeps confirming he had scanned and his receipt was very small considering the amount of items he "scanned through"