I would only avoid it from things like those shops in food courts in large shopping centres.

If you know the shop I wouldn't worry. I eat sushi but only buy it from one place at my work that I know is flat out, and I've never been sick before.

I dont personally take chances with unknown places. I would rather be safe than sorry.

Speaking of which do you think Subway is ok? I've had some serious cravings for it but have been concerned as a friend told me to avoid it.