You are absolutely right. Errors are one thing.
Lifting references from earlier works to folios in archives that no longer exist to give an impression of having done the research, quoting a reference to substantiate a particular point when it says something entirely different and unconnected, appearing to quote from a primary source, when in fact you are taking the quote from a secondary source, complete with the secondary source's transcription mistake and, of course, claiming to have done unique archival research generally, when it is patently obvious that this is not true, are something else - they are deliberate attempts to mislead the reader and are not very intelligent at all, in my view.
If somebody writes a book that is unsympathetic to Napoleon, such as Schom's biography, which I hasten to add I have not read myself, it must be 'innacurate and inflammatory rhetoric and propaganda', 'character defamation', 'not based on solid research', 'highly innacurate' and so on.
Of course Schom's book may be rubbish for all I know, in which case it is perfectly proper to say so, assuming one knows what one is talking about and can produce chapter and verse to show that it is so.
But if this is OK for a book such as Schom's, then by the same standard it must also be OK for equally slanted books by Hamilton-Williams and Bowden.
It is, as you say, a complete irrelevance that the individual might by a 'very nice fellow' or a 'gentleman'.