This article goes through some facts about fast foods. Some is not surprising, some is shocking. Over all, its not really that shocking, chicken picks up beef from the grill and is processed into a chicken-like substance, shakes have gelatin in them. I did find the fact that fries are "meat" flavored surprising, but what I found disgusting was the health violations. I would certainly hope that most reasonable establishments are a bit more food safety conscious than the ones described.
Another article paints McDonald's fries in a bit darker light. I don't know how much truth there is in this, but it may explain why no one I know can make home made fries as crisp.