Well, one of my furballs comes over and begs, no matter what I'm eating. Fish, beef, chicken, whatever. So giving him tuna isn't a big deal since he's going to beg no matter what.
The other one is much more mellow. He sits around, waits for the first one to beg and if the first one is successful, he goes and gets his share of the treats!
I think the second one is smarter. He doesn't get the "no! Bad cat!" treatment but he gets the rewards!
Funny thing is that the first cat only begs with me. When I go away and others take care of them, he doesn't beg at all.