In the age of the internet a lot of information is released every minute. Much of it are obscure raccounts that cannot be fact-checked, and then there are some sources that just plainly have the intention of misinforming. Are there any instances of big assumptions in history that were proven wrong because the primary source in which we based our knowledge was recorded with malicious intent? That someone from the past trolled us?
We do have ways of cross-checking things; indeed, the method that the real historians work with already takes this into account by its very nature. Of course, more can always be said, so if anyone would like to speak further on how historians deal with texts, please go ahead! You'll also be helping a complete bloody amateur at this.
For the meantime, as this question has arisen before, I commend to your attention the following posts: