Well, everybody seems to be forgetting about the history lesson you receive about the Sith in the first game. None of these Sith Masters mentioned, not Ragnos, Kreesh, or any of the others, even Revan, are truly Sith. The Sith were a race of people who existed long ago -- before the Republic, even -- and are now extinct. At least in this part of the universe. The Sith we know from the movies and even from the KotOR games are simply humans (and aliens) who have embraced the Sith doctrines. Now, I'm not saying these are the people that are referred to, but if any people fully deserve the title of "True Sith" this would be them.