The Red Book is well known and usually treated as the best available source of the late 3rd/early 4th age. However, it's pro-western bias is so obvious that the veracy of it can be questioned, IMHO.
In recent years, another narrative has surfaced, though you could just as well say that it stays underground for legal reasons. You may have heard of "The last Ringbearer". You can find the full text REDACTED.
If I may quote an excerpt:
The shining tower of the Barad-dûr citadel rose over the plains of Mordor almost as high as Orodruin like a monument to Man – free Man who had politely but firmly declined the guardianship of the Dwellers on High and started living by his own reason. It was a challenge to the bone-headed aggressive West, which was still picking lice in its log ‘castles’ to the monotonous chanting of scalds extolling the wonders of never-existing Númenor.
Now, obviously, this text is propaganda, but arguably, so is the Red Book. Is there a scholary agreement wether the truth is somewhere in the middle or soemthing altogether different? Are there any archeological finds that support one version or the other?
Historians have generally sided with the account as portrayed in the Red Book, though with some caveats. It is obviously a work of propaganda, with later interpolations by Fourth Age writers in Minas Tirith, but most historians accept a core text that can be attributed to Frodo, or at the very least his notes. The Last Ringbearer is a relatively late text that coincides with the rise of death cults in Gondorian society later in the Fourth Age, as referenced by the fragmentary work, The New Shadow. While the author is anonymous, he was more than likely a member of one of these secret societies attempting to rewrite Middle Earth's history. Besides, we have other documentation dating to the period that tangentially confirms many of the basic facts of the Red Book's narrative.
As someone who studies orc society and who nurses a soft spot for some of the crueler injustices and stereotypes heaped upon them, even I won't go so far as to suggest that Sauron was anything less than a cruel tyrant. The participation of orcs, though not always voluntary, in the wars of the Dark Lords are terrible chapters in the history of orcish communities, something we can't lose sight of.