Aren't all historians engaged in an ongoing revision and refinement of prior historical views? Haven't they always been? Does the term have any meaning beyond this rhetorical attack on some previously held view?
It's also pejoratively used when the "new" narrative exists to legitimize a claim in the present, a view which is sometimes called negationism. For example, official Japanese historiography has historically denied Japanese war crimes and aggression in the Pacific, choosing instead to frame the narrative as a reaction to Western imperialism. On its own, the argument that Japanese entry into the war was partially a reaction to Western imperialist policies is not wrong -- using it to justify Japan's actions in China, however, is a revisionist interpretation of events that exists solely to attempt to exonerate Japan from the crimes they committed.
Historical revisionism works in two ways.
Firstly there's legitimate revisionism which is, as you outlined, the ongoing revision and refinement of prior historical views. Because of our constant revising of history we are able to understand and accept, for example, that during WWII Allied forces did commit acts of unspeakable cruelty, such as the firebombing of Dresden, the murdering of SS guards who had surrendered at Nazi Concentration camps, the forced chemical castration of Alan Turing in the 50's, I could go on.
The negative form of revisionism comes mostly from groups or individuals trying to suppress history. People who, despite overwhelming evidence to the contrary, will insist that certain events either did not happen, or have been greatly exaggerated. For example the political right wing in Japan insists that Japanese Imperial Forces never forced women into sexual slavery as 'Comfort Women', or people who deny or attempt to minimize the number of victims of the Holocaust.
Invariably, negative revisionist history is also associated with tin foil conspiracy theories, linking the Holocaust with a grand international Zionist conspiracy, or even dragging the Illuminati or New World Order into it.
TL;DR Legitimate revisionism is mostly about accepting as fact that which had previously been denied, negative revisionism is about denying that which, in spite of overwhelming evidence, is generally accepted to be true, usually for political purposes.
hi! You may be interested in some previous discussions on revisionism. As for attacks on it, hopefully others will contribute more on that, or it may be worth x-posting to /r/AskSocialScience