Okay, the recent trend by Lucasfilm is that everything is canon, though some works don't quite detailed events as they happened. This said, what in blue blazes is the true story about what happened in the lousy series of six kids' books that included Zorba the Hutt's Revenge and The Glove of Darth Vader? There are plenty of allusions to the Prophets of the Dark Side, Zorba the Hutt, and Trioculus in later works (particularly in reference works like Star Wars Insider articles and The Essential Chronology).
We know Trioculus was indeed an impostor son of Palpatine and the slave lord on Kessel (though how this jives with Moruth Doole, I have no clue), Zorba was released from prison and made life hard for Leia and friends, that whaladons do exist, the Prophets of the Dark Side deemed themselves the rulers of the galaxy (apparently around the same time Issane Ysard did as well), and that Zorba, the Prophets, the weirdo Moffs, and Trioculus wiped each other out.
So. . . .
Did Lando win Cloud City back from the Imperials, only to lose it to Zorba? And did he own a retarded theme park, to boot?
Did SPIN ever exist?
Please tell me the Rebels never had a base on Yavin IV or an academy on "Mount Yoda" on Dagobah.
Ken was a figment of someone's overactive imagination, right? And that question goes double for Triclops.
Was Vader's right glove indeed made of indestructible materials for whatever moronic reason? And was there someone in the Empire smart enough to become a pretender to the throne but stupid enough to think that Vader's glove is what allowed him to choke people? And was he cliché enough to have a serious enough crush on Leia to try to force her to marry him?
Did Ranats take over Jabba's Palace?
Okay, we know Leia and Han didn't get married twice. That's a given.
Did the New Republic have more important matters than environmentally-themed adventures, or was Rogue Squadron taking care of all those concerns?