Collecting information about customers has gotten easier than ever, but much of what's collected is just easy-to-get and not easy-to-use. Keeping data clean and useable is expensive and you better know why you're maintaining it.
O'Reilly Radar: A Good Nudge Trumps a Good Prediction, 2014-Jul-18 by Simon Chan
In this case, I was going to buy cereal and milk anyway, regardless of the accuracy of the prediction. Although my customer experience is probably improved, I do not necessarily buy more stuff. If the aim is to increase sales, the metric should, for example, focus on how well the model can predict and recommend products that will nudge me to buy much more than just cereal and milk.