ACM used to routinely request certain kinds of "volunteered" contributions
and/or subscriptions on my annual invoicing. They would do this by adding
the things they wanted me to do (without my requesting it) and make me
have to line out the items I didn't want.
This is known as "Sneak Into Basket": http://wiki.darkpatterns.org/Sneak_into_basketIf anyone has a copy of such an invoice (I've always thought "societies" were silly, never joined ACM when I was in grad school, and refused to join NHS on principle) they should throw a copy up on the Dark Patterns wiki.
¹ Racist nomenclature thumbs down