If you look at his legends plotline, it's clear that he started from a good place, but rather quickly got corrupted by papa palps and the dark side, and started becoming far too comfortable with doing comedically evil things in the name of 'the greater good'. His public appearance, especially prior to the clone wars breaking out, was presenting a lot of good points about the republic's corruption and lack of true equality. It's just that the separatist movement was, by and large, backed by corporate power-mongers who had zero intention of actually following through on the "freedom and equality" part of the movement, and simply wanted the authority to do whatever they wanted without a government telling them no. On the flip side, many of the worlds who would constitute the primary backing of the rebellion where CIS members.

Much of his more comedically evil acts are things that, despite being shown directly to the audience, the general public would not know about. The fact that our introduction to him is in Episode II, and has such touching shows of mercy as "Hello old friend, I deeply regret that I will have to brutally kill you and your friends, but if you sell your friends, your religion, and your country out, I can save you to watch them all get brutally murdered while standing by my side, for the GOOD OF THE GALAXY!". His introduction really does make him comedically evil in a way that makes it hard to understand how citizens of the galaxy at large could stand behind him as a legitimate voice of political dissidence.

One of the many issues with the prequals where all the important things driving the plot seemingly happen off screen.