I would say you must try anyway, but be prepared to pay. I have a SFGAm parking pass (on a SFOG season pass), and did NOT have to pay at SFA (last summer) or SFWL (this summer). Maybe the staff did not know any better, but trying is always worth saving the $10 or so when you can. We didn't have the parking pass yet when we were at SFOG this summer, so I am not sure if it would have worked or not. I really think it depend on the person who is checking and if they understand the policy or not. But you have to try!!
Think about it, it takes less time for you to flash them your parking pass and see if they say yes or no, than it did for you (or me) to make these posts :)