I would really, really, really like your opinions on an issue. I was raised that when you are invited to someone's home, you bring a hostess gift, and at the very least ask to contribute to the meal in some way. Further, when you bring something to someone's home, it is considered a gift. For example, if I am going to a potluck and my dish is not fully consumed, I am only entitled to return home with my Tupperware, not the food that was in it.
I have had people come to my home take back something they brought. I have also had people come to my home with a contribution to the meal/event and get put out if I did not serve their contribution right away (imagine they bring a bottle of wine but there are already three other bottles open, of course I would wait to open a fourth!) Worse is if you don't use their contribution right away and they nag you about it on subsequent visits, but that is an entirely different Emily Post post.
I was in charge of snacks for bible study last week and I overbought considerably. I helped tidy up and left the remaining food behind for the hostess. She didn't offer or insist I bring it with me and I was 100% fine with that. I would not expect otherwise. Coincidentally, it was my turn to bring breakfast at church that week. Someone suggested I should bring the leftovers from the bible study (also another Emily Post post, lol.) I replied that I had left all the leftovers behind, and I received several quizzical stares.
So my question is, what do you do when you contribute and there are leftovers? Would you ever rescind a hostess gift? Is this a regional issue, an etiquette issue or something entirely different?