Infection control problems using single use vials?

During orientation for my hospital system's, the IV nurse educator said that the single use vials of normal saline we use are manufactured with porous plastic caps, so after breaking off the plastic cap, we should swab them with alcohol.

I work in an "outlying" hospital, and NONE Of the nurses I work with swabs off the rubber tops after removing the new caps, and they think I am crazy and wasting time. I have no idea if this hospital uses the same NS as the other hospital in the system that nurse educator is from. I do know that once I remove the cap, I see little "stars points" in the metal foil on the underside of the plastic cap-- it looks to me like that is how the cap was attached, and there MIGHT be gaps in the metal between these points where microbes could enter before the plastic cap is broken off.

Is there any way I can tell whether I need to swab the rubber tops, or if it is indeed a waste of time? The label indicates they are single use Hospirus 0.9% normal saline vials, but there are no instructions about cleaning the tops.

Thanks,

Greg