Adding surface scratches I recently saw Andrew Price's tutorial on how to do realistic texturing.  At the end of the tutorial he said something along  the lines of needing to just "add scratches" to increase the realism.  How do you simply add scratches?  I understand that there are probably multiple methods, and I am interested in hearing as many as possible.  Thank you.
The way Todd is completely right,but you can go even complex for scratches,like using the pointiness feature in blender,here I used two different scratches texture to do the material,check the node tree for more information.