Very true. Not all of them, but the majority at this point. If you want to know if a history book is bullshit, check the inline citations. If there aren't any, it's trash. E.g. Howard Zinn's A People's History of the United States. If there are, check the elipses... That's where historians get all their power to lie.

Check the bibliography. Good history cites almost entirely primary sources. Fake, ideologically driven history mostly cites other historians, i.e secondary sources.