Personally, if I have to occasionally clean pins/contacts, once any loose dirt is removed, I scrape very gently with a scalpel blade or similar, since that seems to clean things without removing actual good metal.
Sometimes the battery contacts need a *very* gentle teasing-out to make better mechanical contact with the pins. The contacts don't stay shiny for long, and still seem to work much of the time even with the regular dull surface. I guess it's possible that if mechanical contact is borderline, cleaning the contact to shiny metal may temporarily fix things, but that as soon as the regular surface film returns, the contact goes back to being poor, especially if a little metal is being removed each time.
I'd be tempted to try teasing out the battery 'petals' slightly (and I do mean slightly), and see if that makes much difference.
You *can* get accelerated corrosion due to current passing through contacts if they're damp - it's possible that a tiny bit of grease might help there, though it may need fairly regular cleaning out and replacement if there's a chance it could pick up dirt.
I'd have thought it reasonably unlikely that anything worse than water was getting on the contacts. Presumably, even if a cell was venting slightly, there isn't a path from cell to external battery contact?
