Just because OR books are a good read, in no way makes them accurate.
All four of these books are heavily researched and referenced by Martin Dugard. Footnotes and bibliographies. At least as much as many history books I've ever read. Could some professor who's spent his whole career studying one incident in history get it more accurate? Probably but who's read their books? Probably no one. They'd be too dry and boring.
Look, I am not a big fan of O'Reilly personally, even though I do occasionally watch the O'Reilly Factor. But to summarily criticize the accuracy of these books because you don't like O'Reilly and without having even read the books, I think is disingenuous.