I am quite familiar with the SME 20/12 > SME Series V and am quite happy to vouch for it being a stellar performer.
I am as a listener quite attuned to detecting smearing and small distortions during a replay. My experiences has allowed myself on a few occasions to offer suggestions on methods to decrease the noticeable presence of the unwanted information.
Sometimes a thorough stylus clean is enough, on others a selection of Puck weights can offer an improvement and on the the odd occasion it has been suspected that a Platter Spindle Bearing is not functioning at its optimum.
A very basic treatment of a few drips of oil added to the Spindle Housing has yielded a much improved result, a subsequent servicing of the bearing housing has created a perception of a very good improvement having occurred.
I don't think a TT manufacturer would randomly select a TT to be used for testing and supply the Technical Data for their Models. I assume this will be carried out a TT, that has had a little post production attention. Measurements offered for the TT are not guaranteed to to be maintained for the usage life of the TT.
They are probably expected and designed for, to last the warranty period only.
What average TT owner would check for evidence of the deterioration of the Tech Data Info' ?
I have no recollection of any perception of the SME 20/12 producing any unwanted smearing or distortion during a replay, so I will assume the design for the SME bearing is able to be maintained at a optimum for many many years after being new.
That is not the case for all TT's, I have purchased TT's with a questionable bearing condition, especially when assessing what has been discovered and how it would impact on the function, whilst inspecting the internals of the housing. I also know others who have shared in this same encounter, and following a few simple procedures attained a much improved functioning part for their TT/TT's.