Eight years ago I did some work with a chemicals company. One of their divisions made paint and wanted to invent a framework for innovation. One of the things we did was get into bed (not literally) with the customer complaints manager. We figured that what people complained most bitterly and most frequently about was probably an area where innovation should be pointed. A few years later one of the products that came out of R&D was a white paint that told you about which bits of a (white) wall you’d forgotten to paint.