For all the places that were mentioned in this thread, there are the same restaurants in other places that are just fine to eat at. Case in point: McDonalds. The McD's by us is one of the best ones we've eaten at. Their fries are always fresh, and they have rarely (if ever) screwed up our order.
But as a general rule, we don't go to Burger King, mostly because my wife just doesn't like the food. I don't have a problem with it, but it's not worth fighting about.
We don't go to KFC either, mostly because they've closed almost all of them around here for some reason. But everytime I have eaten there in recent memory, I always had to make a dash to the restroom...