the problem with subway is that they don't change their gloves often enough. and also food gets contaminated by traces of other food. For example, as a vegan i have no animal products at all. The guy infront of me in the q gets a meatball sub, So the assistant puts cheese on the sub, the (with the same gloves) put's his hand in the salad, onions, and peppers, before putting the meatballs on. Then after asking the customer if he wants anything else, the customers requests some more salad, so without removing the gloves (which now have sauce from the meat, and cheese on) he dips his hand back in the salad.
So when i come to get my sub, the guy changes his gloves, but there are already traces of other bits of food all over the place. And that goes on every time someone eats a sandwhich.
It doesn't cause problems because there is such small amounts involved, but as a vegan i don't like the thought that there might be traces of meat or dairy on my food.
Sorry to rant, but this never comes up in conversation, and i am glad i have my chance to vent!
I used to eat subways a lot, and they are not amazingly unhealthy (if you get the low fat ones and don't have cheese, or white bread), but i wouldn't go back and eat there.