Edge detection and cavity masking are very important characteristics of procedural materials. Edge wear is common to any object with age along with cavities and crevices that are constantly attracting dirt, dust, and grime. So it's a good idea to know how to generate procedural factors (masks) for edges and crevices.
The "pointiness" attribute was the best procedural edge detection we had for a long time. But now with the addition of the bevel node, we can do better. Similarly baking an ambient occlusion texture was one of the only ways to mask cavities. Now Cycles has a built-in AO node that's much more convenient.
With Blender 2.80 or experimental builds of 2.79b, let's explore how we can generate various type of wear and tear effect without leaving the node editor.