To objectively measure the efficiency of a cleaning process, you always start with a known contaminated standard and then measure how much of the contaminates were removed. This is generally accomplished with parts of a specific area and weight with a known weight of standardized soil applied, and pre and post weights are compared being one criterion, another being a wash with a powerful solvent to measure non-volatile residue (NVR) and another being a particle count. High magnification could also be used, but the inherent problem is field of view - you end up looking at a very, very small area. For large surface areas, and complex geometries (i.e., a grooved record) often statistical measure are applied based on allowable contamination (NVR & particles) per sq-ft or sq-in or for semi-conductor chips much smaller with crazy NVR and particle count requirements.
But the record presents a unique situation since every inch represents valuable data. So, a small area sample would likely not be representative requiring a larger area which then adds a lot of complication to the test. Record contamination with hard non-viscous detritus (such as a particle) can cause the ticks and pops, but soft viscous detritus (such as a cleaner residue) can cause loss of high frequency information.
If you read this article on UT, pay attention to the particle cleaning efficiency between 40-kHz and high kHz - awad-reprint II (crest-ultrasonics.com); Recent investigations have confirmed that higher frequencies are more effective for the removal of certain contaminants. Reports on particle removal efficiency have shown that the removal efficiency of one micron and submicron particles in deionized water has increased with the higher frequency. At 65 kHz, the
removal efficiency of a one micron particle is 95 percent, versus 88 percent at 40
kHz. A similar increase in efficiency results was reported for 0.7 and 0.5 micron particles.
If you did a rigorous record cleaning test, you would more than likely find that there were efficiency differences in any single step with different equipment and different chemistry but combined in a process of pre-clean & final clean they could all yield very high cleaning efficiency with only small differences at the higher end with higher end not necessarily defined by the most expensive process. A lot of expense is for convenience.
Just some thoughts.
PS/Precision cleaning processes, cleaning efficiency and cleanliness verification is something I did for the Navy for 20-yrs for high pressure oxygen (and other compressed gases) and life support systems.