I have to amend my last statement. The main period I study is the Tudor court under Henry VIII, and when it comes to Anne Boleyn one of the only accounts of her rise and queenship is Eustace Chapuys, who was Spanish ambassador and very close with Katherine of Aragon so very bias against Anne. While necessary to take with a grain of salt, much of what he said can be substantiated in other written records so you can't discount everything he said.

With regards to detractors of Napoleon, I would be wary to trust what can't be substantiated elsewhere. Plus always keeping in mind that they may very well have an axe to grind.