Merkuri
Explorer
They go and see a cat. Oh hey, stray cat. I didn't just say there's a cat on the steps. Its a stray cat, and obviously so. Good deed to be done? Give it a home or find whom it belongs to.
I'm sorry, I would not have gotten that. A stray cat is not unusual, so the word "stray" wouldn't make the cat stick out to me. There are some strays that hang around my apartment building. We're told not to touch or feed them because they're feral, and they might bite, so my instinct in real life is to stay away from cats I don't know.
Plus, some people would say a stray cat is happier than an owned cat because it's free. These people would say that finding the cat a home would not be a good deed.
When I think "good deed" I think of helping an old lady cross the street, or giving food to a beggar, or returning a lost wallet. Boy scout type of things. Or, if I were told that I needed to do a "good deed" in a D&D game I would probably expect a plot hook for an adventure to turn up soon, where the completion of the adventure would be the good deed.
My point here is that not everybody thinks the same way. Something you think is perfectly logical may not make sense to someone else.
I think your mistake was that you had one single good deed in mind - one solution. DMs should try to avoid situations that boil down to "guess what solution the DM is thinking of." Always have a plan B, or at least allow your players to succeed if they think of something you did not. If I were DMing the scenario you mentioned I would have let the players succeed by donating that deer meat to the church. It fits the description of good deed and it's creative, so they deserve to be rewarded for it, IMO.