A relatively common way in which consumers can abuse SCO systems is to misrepresent what a product is when it is being weighed – the ‘grapes for onion’ scam. Here the consumer places, say a bag of grapes on the weigh scale, but ‘tells’ the system they are in fact onions, which are much cheaper than grapes. Some retailers are beginning to try technologies that will ‘identify’ what the product is that is placed on the weight scale, or in some circumstances what it is not. In this example, the system ‘knows’ what onions look like and so when the user presses this option, the system generates an alert to say it hasn’t ‘seen’ onions. Again, this is challenging technology to get to work in a complex environment, especially when a store could have as many as 50,000 different items and there is little tolerance for delay while scanning.