Despite being the most connected and analysed than we have ever been in human history, and the huge amount of resulting data available today, we still fall victim to "fake news". In an era when news, at best, moved at the speed of horse and most people only got as far as the local market town things were unlikely to be better. Localized opinions, such as the Paris Mob or the Vendee therefore had a disproportionate effect. Censorship in European regimes was commonplace, meaning the transmission, formation or adoption of a distinct national opinion that differed from their rulers' propaganda was difficult. In an era of secret police, commiting opinion to paper was dangerous for the literate and of course impossible for the illiterate. What we really need is a impartial diarist or two, wandering the streets of Warsaw, recording what they heard and saw.

Discerning true opinion was probably difficult then, at a distance of two centuries nigh impossible. The measures you outline are really just proxies, and so open to misinterpretation. Add in our modern prediliction for historical fashion and the ready availablilty of Napoleon's (and others) aspirational propaganda and it's hardly surprising that myths take root. We should take care in countries which have seen regimes that have practiced redactive history. It's laudable when an interpretive discipline makes a foray into empiricism, but you can't make bricks without clay.