McDonalds, Burger King, TGIF, KFC...well you get the picture. Avoid most any chain restaurant.

As for others, it's hard to say. I try to quickly forget the bad ones so I can't really remember many. And by US standards there aren't any bad restaurants within perhaps 200 miles of where I live in Burgundy.

I do recall a particularly bad restaurant in Oak Park, Illinois because of the name. It's called Poor Phil's, but I renamed it Poor Choice.