I'm fortunate in that I've never known anyone who was such a bad cook that even the dog refused a bite.
Most of the bad meals I can think of are recipes I don't like, recipes that got done to death by the cook, or some freak accident that turned a good dinner into a terrible one. I can think of people in my family who made things that I positively hated--but each of these people also made things that were very good, and sometimes something I haven't seen duplicated elsewhere.
Of course, I have bad days in the kitchen, too. Indeed, since almost meal I've eaten recently has been prepared by me, I guess I might actually be forced to give my Worst Cook of 2011 award to myself!
In a way, I think the worst cooking on average may be convenience type items--frozen and canned dinners, etc. Some products have been unbearably awful. Even at best, there is very little that I think equals what a decent cook can do. At best, many convenience products often seem bland--and I wonder if it isn't by intent so as to maximize sales. Boldly spicing might interest some customers, but might lose other sales.