Basically, to be more serious about it, MX Brown technology is inherently enormously "multi-scratchy". For a single key press, several different friction events appear to occur of a plastic-on-plastic nature that create an amalgam of noise, synthesized from the several weak forces. In practice, the key, especially in unison with other keys, sounds like an "old toy", it's plastic-on-plastic sex.
One can even be more forceful about it and try to press a switch while also inflicting force on either of 4 horizontal directions. In all 4 directions the force of friction applied is enormous for the size of the small key.
Result? The switches must always be oiled. The opinions differ on how, but I think those keys are by inception so scratchy I see no argument at all at how non-oiled they could be better (I would discount 'nostalgia/used to it' type opinions).
edit: And I think the tactility event remains even with high viscosity oils.