It seems clear that Snowball is not doing the things that Napoleon blames him for. He flees the farm after Napoleon attempts to have him killed using his dogs, and after that he becomes a sort of bete noire on the farm. In speech after speech, Squealer claims that Snowball is not only colluding with humans on the outside to overthrow the farm, but that he is actually infiltrating the farm in league with some of the animals to overthrow Napoleon. Some of the animals confess to the crime, but it is clear that they have been brainwashed, so to speak. Squealer also goes to great lengths to rewrite the history of the farm in such a way as to minimize Snowball's role in it. He even claims that Snowball played no role in the battle of the Cowshed, a claim that seems odd to some of the animals:
"Snowball was in league with Jones from the very start! He was Jones’s secret agent all the time...To my mind this explains a great deal, comrades. Did we not see for ourselves how he attempted — fortunately without success — to get us defeated and destroyed at the Battle of the Cowshed?”
The animals are confused, but for the reader, this is clear evidence that the entire reimaging of Snowball is based on a series of falsehoods. Orwell has clearly described Snowball's role in the battle as that of a hero. So Squealer's and Napoleon's attempts to vilify him are based on a huge lie, one which is intended to create a sense of crisis around the farm so that Napoleon can justify his rule. It is reasonable to assume that Snowball has not done any of the terrible things he is accused of.