(For use in Arkham Horror)

If I sleeve a rather tall stack of cards (small or large) that has cards from a few different expansions (and thus, all slightly bowed in different orientations by expansion), will these sleeves:

(A) cut down on that annoying "frictionless spin" that oddly bowed cards tend to do when at the top of a deck?

(B) do anything to help "flatten" a card?

I don't know what size Arkham Horror uses, but I just tried stacking a tower of the FFG Silver package sleeves using your bowed method. And there was no slippage, top deck was pretty sturdy.

As far as flattening the cards...when you sleeve, it tends to make your cards thicker and hold shape, if your cards are bent or curling due to moisture, sleeves would help protect them and presumably flatten them.