What we know: In "Durka Returns", Captain Selto Durka somehow busted the (permanent) mind cleansing that the Nebari had inflicted on him for over 100 cycles. Rygel, due to his high metabolism, also busted the (temporary) mind-cleansing enflicted on him by Varla and Meelak. John, due to the Scorpy chip, busted the (temporary) mind cleansing inflicted on him by Varla and Meelak, as well.
What I can speculate from this: Nebari mind cleansing is, at it's roots, defective.
What could this mean for our intrepid crew? I don't know. If Durka gets recaptured by the Nebari, they're going to test him, and find out why his permanent mind cleansing broke. If they never did capture Durka again, yet they managed to capture John or Rygel, they just might test him. The mind-cleansing done on John and Rygel was temporary, which means it will wear off.
How would they know John's been mind-cleansed, you ask? Those drug-dispensers Varla and Meelak's machine stuck to his optic nerves didn't seem biodegradable. They're probably still attached to his optic nerves. If the Nebari capture John (or Rygel) again, it's mostly likely that they will detect the drug dispensers, and know that John (or Rygel) has been mind-cleansed. And, if the dispensers have a kind of Nebari serial number on them, they might be able to trace them back to the incedent where Varla was killed. Then they would realize that, somehow, someone who was mind-cleansed by Varla on Moya broke through the drug-induced barrier, and managed to outthwart her.
The end result of all this testing? The mind cleansing technology that the Nebari have used for over 100 cycles would probably be declared defective, and scrapped for some kind of new technology. I don't know what, though.
Durka. I mean, if they captured Durka (who was subject to permanent mind cleansing for over 100 cycles) again, and realized that he broke free, heads are going to roll. That would most certainly get the whole system declared defective. And without mind cleansing, the Nebari resistance would grow. And Nebari-agitators would become less afraid. Granted, they still have their horrific weaponry from the Nebari virus, to the Command-Carrier-Destroying-Cannon, to the thing that can rip through dimensions (see TTLG), but without mind cleansing, they no longer have an easy way to subdue small groups of people (the guns work perfectly well on a large scale, but do you really want to point a Command-Carrier-Destroying-Cannon at a guy named Bob? No, you want to point it at Command Carriers. Bob gets mind-cleansed. Using huge guns on one or two [or 7] people is inefficient).
End of article.