My experience in signing up for the cards was fine, and the ladies who processed us were pleasant and professional. The buffet opened at 4PM, so my wife and I arrived 30 minutes early and signed up for the card. I thanked her and had a nice experience with her. After several minutes on hold, she verified that the discount would be applied upon receipt of a Player's Card.
I was unable to verify on-line whether or not this was true, so I called them and spoke with a representative who didn't know anything about it, but was kind enough to check. My wife and I were told that the Hard Rock offered a 50% 'Senior Discount' on Wednesday's for their buffet, to those 55+.