Originally Posted By: OilFilters
... Out of habit, I normally wipe it off. ...
As for "inspecting" it, I couldn't see the gasket surface anyway unless I used a mirror. ...
Likewise, on my Mazda; I could easily feel the mounting surface and wipe it, but could not see it. If one isn't careful to clean the mounting base, contamination is likely whenever the new filter gasket has a larger diameter than the replaced one. The filter should catch any stray grit that makes it through the entry holes.
That whole issue is obsolete now, with cartridge filters.