1. All tune sandwiches are good. By definition.
2. Best tuna sandwich I ever had was bought at a 7/11 and consumed at a motel after a long day of driving, along with chips and cola, while watching CNN. Don't know why, maybe it was the pickle relish, maybe it was just my perception at the time. Long day driving, then rest.
3. Finally figured out why we southerners usually say tuna fish rather than tuna. (Or at least a logical way to explain it even if it isn't the real reason.) The fruit of a particular cactus is called tuna, hence I surmise tuna fruit is a valid term. To avoid confusion . . . Anyhow, you are probably thinking at this point . . . .