We know he knew about the Hellmouth and all the weird occurrences in Sunnydale. But did he know about Buffy being the Slayer and the Mayor's Ascension? For the latter it seems the answer is no given his reaction in the finale of season 3. For the former, I don't recall him ever using the word Slayer. Is it possible Snyder wasn't really a villain all along but just someone being manipulated by the Mayor?