Subway isn't that bad, if the stuff hasn't been properly refrigerated/ refreshed, you can see it wilting. If the spinach/ spring mix is stiff, and "green", most of that stuff should be fine.
Subway is a great place for veggie peeps, because you can make anything taste awesome with their sauces, though most of the sauces might contain milk powder or something.
The worst fast food, is the tiny sushi places spaced between 5 massage parlors. If you notice a string of cheap motels, and inter-spaced with 5 different massage parlors, you know this is an asian gang place, and those are not massage parlors.
Anyway, back to the sushi, it's just awful, and EXTREMELY-RISKY. You will almost certainly come down with something. They also use really cheap farmed salmon, it's gross. Salmon is gross in general, but the farmed stuff is inedible.