Examples of uses

As glossiness or anisotropy maps, to add realistic surface imperfections to reflective surfaces such as glass, metal and plastic.

Bump maps for realistic micro-scratches, for creating subtle impurities in materials like plastic and paint, and more.

Extra detail on windows, monitors, mirrors and other reflective surfaces that require that extra glint of realism.

Texture painting stamps and brushes source material. 

Masks for layered materials and procedural shaders. Combined with triplanar mapping, you can quickly create complex materials, with worn edges and dirty crevices that adapt to any geometry.

Overlays on lens flares and glare in compositing, emulating dirty lenses or camera housing. The raw, full color scans are especially suited for this.

Mix with plain colors in your materials to break them up and add variation. No color is perfect.