I've noticed that some of the journals I submit to, most of which are top tier, have optional costs. For instance, there is an optional page cost that I could pay even though my paper is not open access and is under the page limits. This cost is revealed upon acceptance.
I've always said no to pay it, but I wonder why the costs exist in the first place and if it's bad form to say no?
EDIT: I just realized how arrogant it sounds to say "most of which are top tier" :-P I meant "most of which are reputable journals that would not appear on Beal's list.