i agree that wd can leave a film but i’ve never seen one problem caused by it.
has no one ever seen a wet dist. cap (the inside, not the outside)?
i’ve seen a few that were not only damp but actually dripping water when removed.
the caps/wires were bone dry on the outside and saturated inside
due to high humidity many times spraying the cap down with wd was actually recommended SOP when performing a new car pre-del. inspec. or servicing a used one