Wow, the replies are just flying... Just to follow up on what Hmmmmm said... I'm wondering when Sis could have become aware of the (very soon) expiration date for the dinner. Was it stated on the auction card that she had a chance to look at, or was she only informed of it when she was given the voucher, after she paid her money? (I know she didn't actually realize there was an expiration date until later, but I'm wondering when the first time someone could have known about it was.)
I mean, let's say I'm walking around the church auction and I see a card for "Turkey dinner from Joe's Deli, XYZ components, $50 value." No expiration date mentioned. While I might consider that there could be an expiration date, I wouldn't reasonably assume it was any time soon. So I bid and I win and I hand someone my check and in return I'm handed the voucher, and at that point, I see for the first time that the dinner must be picked up within just a few days. And that just doesn't work for me, because I'm going out of town (not unusual for Thanksgiving) or something else. Basically, the expiration date would've been an easy piece of information to include in the initial description, and if I had seen it, I wouldn't have bid on this item.
Now, maybe I decide to just let the church keep the $50, and I think of it as a pure donation that I get nothing in return for. But even so I would want to let them know that I was disappointed with the poor communication. I would think the organizers would want to know about that. Because next time there's a church auction, I'm going to be walking around looking at things and thinking, "Hmm, this is nice, but I wonder what the 'catch' might be," and I'll be less likely to bid on anything.