Kamino - not on the maps
Without doubt one of the stupidest, most arbitrary and illogical things in the prequels. And that's saying something.
Why isn't it on the maps? So people wouldn't know about the best cloners in the galaxy? So that people who know about it couldn't find out how to get there (if they hadn't been there before I guess). Because people would have no use for it or reason to go there unless they happened to find it on a map?
If it's not on the maps and kept a secret from everyone, how do they do business? Surely the Republic (they think) isn't their only customer. Because if they were then there would be plenty of correspondence between the cloners and their customers. "Dear Republic. Clones progressing fine. Not had any visitors in years though. I wonder if we're still on the maps."
But Dex, Dax, "American" diner fellow has heard of Kamino. Surely he's not the only one. So it's not even a secret.
Ok then. Maybe Kamino isn't in the Republic so people in the Republic don't care and wouldn't notice if it wasn't on the maps. But they're big enough to supply the GALACTIC REPUBLIC with a grand army. And they're outside the republic? Who else are they supplying so many clones to (since they have the capacity already)?
This "they're not on the maps" nonsense is just idle intrigue that Lucas added to make the mystery seem clever. But given all the stuff I've mentioned, the Jedi should have been thinking, there's something seriously unreliable about all this BEFORE they even laid eyes on the clone army that they just accept as a means to an end without any further scrutiny. It's like Lucas telling the Jedi that this is dodgy more than it's telling the audience. And it makes the Jedi appear considerably less intelligent than the below average audience member.
Utter garbage.