A quick model of a Lego Brick with stains made with Maya, Knald and Substance Painter. I exaggerated the dirt a little bit as the roughness was a bit difficult to see.
Lego Brick Final Render
Lego Brick Final Render (Bottom)
Lego Brick
Substance Painter Texture
Lego Brick High and Low Poly
Lego Brick High and Low Poly (Wireframe)
Lego Brick High and Low Poly (Bottom)
Lego Brick High and Low Poly (Bottom - Wireframe)