vilters was referring to the nodes attached to diffuse channel. you can delete the connections to the diffuse channel and it will look more realistic when rendered.

however, if you simply set diffuse channel to zero, then that has the same effect on render, whilst allowing for better preview of texture prior to rendering.

if the texture you used is EZSkin 2 or later, then don't delete any of those nodes, as they're necessary for alt diffuse and alt specular in PP2014 and earlier. PP2016 will simplify this so that you won't need all those nodes with the new PBR renderer.