Interesting, Flying Lawyer.
Bolts are often used to clamp load bearing assemblies, so may have to handle a range of loads. Normally the bolt would be sized to apply sufficient force for friction to stop the clamped join sliding at max load. Gloss paint could well affect this, and once movement starts the joint will quickly deteriorate. Worst case is that bolt has to withstand full shear load - they are not good at this. I imagine surface after wet'n'dry sanding would provide a much better grip.