Wretched Hive: The planet Nepscia (Galith Waste) is the canonical example. Its primary inhabited portion is one large red market – which is to say, it’s one giant bastardized offspring of Jackson’s Whole and Tortuga. It’s a… fun place to visit in the right frame of mind – but go armed, more armed, and even more armed, carry and use liberally your poison and drug detectors, and take plenty of bribe money.
In a less-physical place sense, go take a look at some of the virtualities, data havens, archives and memeweaves in the filthier parts of the extranet or outright blacknets sometime, too, huh? Just be sure to have a good virus checker. For your brain.
(For my fellow Effectors of Mass: Not, however, like Omega. Most of Nepscia’s population outside the cream of the ruthless kleptarch set would love to move somewhere as orderly and well-run as Omega, or failing that, spend all their days praying for someone like Aria T’Loak to move in and, if not clean the place up, at least keep the dirt from splashing around so much.)