Has anyone tell us what they mean by a 'clean' 78, or a 'cleaned' 78.
It makes more sense to have a contest between machines after agreement about how the 'clean-ness' of a 78 is measured. I am no expert, but here are some possible criteria, and I suppose you could give a numeric weight to each measurement to come up with a cleaning 'score'. I am sure there are many other measures that could be taken, like actual signal to noise ratio and the like.
1) presence of dirt or microscopic metal particles in the groves.
2) Lowest noise levels in a quiet section of grove.
3) Lowest ionic contamination ( part of the 'cleaned' record is dipped into distilled water and stirred. Then the ohmic resistance of the water is measured, the resistance will drop due to ionic contamination).
4) The record after cleaning sounds better, has less distortion, less residual noise in quiet parts of the grove.
5) The record after cleaning has shinier surface. This could be due to dirt removal or actual surface polishing, but this could be due to residual oils or soaps also, which is probably not a good result.
Other thoughts about measuring the effects of cleaning:
Is it possible that some dirt in the grove acts as a lubricant, so the needle moves easier than it would after cleaning?
Is it possible that some dirt in the grove fills in defects and pits in the grove walls, so that after cleaning the amount of surface noise is actually increased?
It is possible that a cleaner would 'add' a surface treatment, like a a polymer that would harden and fill in tiny imperfections in the surface, like some 'resin' car waxes