Let me explain , there are a ton of bad books that get popular (grand stragety of the roman empire,guns germs and steel) , way to dated history books(decline and fall of the roman empire by edward gibbon), and books that some how got published by a academic press (The First Fossil Hunters: Dinosaurs, Mammoths, and Myth in Greek and Roman Times).
By compiling them here we can inform people what books not to cite on here and quickly refer to links when asked questions about such books.
As an alternative, wouldn't it be better to list more threads about these books in the FAQ? Guns, Germs and Steel for example is already there: http://www.reddit.com/r/AskHistorians/wiki/historians_views#wiki_historians.27_views_of_other_historians
I think it would be better/more effective to do that than just create a sort of 'black list' of sources. A discussion of where a book has gone wrong, and if it has any redeeming features, is probably more useful than just saying that a book is bad and that no one should discuss it or use it.
What about these books are you considering "bad"? Just curious.