Yeah - I think that glossiness is a polish effect overall so you can have smeared effects (finger prints on glass as an example) which wouldn’t cause the surface to actually raise in any way. You might use a bump and glossiness map if you were doing something like a mix between two different materials like dirt on a surface which is really mixing between two totally different surface types. Looking around my desk at the minute, I’ve got a leather surface and lots of plastics. For the (p)leather desk surface I’d use a bump for the actual cellular pattern and then use a single glossiness value to start. The bump will change the normals of the surface and make the little valleys receive light differently to the flat sections so that’ll likely be enough to give me specular variation. If you were to use a glossiness map there too, it’s not as if the little valleys are made out of a different material or would have different properties than the flat facing parts so why try and map variation in there? Toitally different situation if you’re doing something like the indents in a surface collecting dirt or dust but then you’re again looking at mixing between two totally different materials.