As a young man I was introduced to the economics of grand theft auto by a person of the world.
A stolen vehicle (in Brooklyn at least) never made it to a new owner in one piece. It turned out it was far more lucrative to disassemble it and sell the parts piecemeal. Mind you were talking about the fairly common mass produced cars here: Fords, Hondas, and such. Stealing a Lamborghini might be different, if you could find a Lamborghini in Brooklyn. So the stolen cars get the filleted and the unsalable parts get dumped in a scrap yard somewhere.
It must be much the same with starships, captured by pirates. Every ship in a pirate fleet (if you even wanted such an organization) needs maintenance, supplies and fuel. The theft possible in a given area will only support so many ships. So unless a pirate has an immediate need for a ship, they will unload it and usually in pieces. The most valuable parts of a ship are, of course, its engines and generators allowed by computers and electronics. Low berths are low cost but can be dismounted easily and moved quickly.
Dismounting an engine is best done in zero gravity, ideally a pressurized orbital dock that provides a shirt sleeve environment. Usually that's not possible and you rough it in orbit and use remotes or crew in spacesuits. Such out of the way places usually have a base set u to hold specialized equipment, craft and extra mechanics. In fact a few become thriving businesses, buying ships outright and breaking them down,
Right behind the pirates come the real reavers who intend on separating the pirates from their money. Camp followers, gamblers, merchants, dwellers in houses of ill repute. Any pirate base will attract these alpha predators. They will grow and attract more merchants as the frontier gets closer. When the frontier officially passes the planet by the pirates will usually have departed. What happens then?
1) You have a new colony asking to join the Polity and thanking them for chasing those nasty (and probably broke) pirates away
2) The camp followers, gamblers, merchants, dwellers in houses of ill repute ,as well as the craftsmen and merchants pull out and go somewhere else, a civilized world or another pirate haven.
Case #1 happens way more than the government types admit. The locals clean it up for the history books. I'm not judgmental but pointing out the local ruler's ancestor was a sex slave to a pirate king sounds a little dangerous to me.
Case #2 is less common. The planet is abandoned. The hulk in various states of salvage and repair litter close orbit. Note in many cases the money changers following the pirates will live on some, if there's no better alternative.
In case #2 you will have a sargasso in space. You'd have a sargasso in case #1 unless the people on planet got to worrying about their image and started cleaning up the empties but a sargasso orbiting a deserted planet or moon has more atmosphere.
Random Table ("What am I doing in this forsaken Sargasso?!")
1- You have a salvage operation!
2- You need a part you could get cheap here!
3- This is where the 'X' is on the treasure map! the treasure must be onboard one of those hulks!
4- Misjump. Perhaps you can scrounge enough fuel from these wrecks to keep going?
5- You're patrol posted. This is a good place to hide. Provided no one needs to salvage something on your ship.
6- Historical research.
1- No engines or power plants. Fuel drained. Secondary systems (4 in 6 chance) are mostly in ruins. Most of the ship is in vacuum.
2- No engines or power plants. Batteries or solar cells are working providing light, heat and some gravity. Secondary systems (3 in 6 chance) are present and working. Life systems hold atmosphere.
3- Engines and power plant may be present (2 in 6 chance) and all secondary systems are working at nominal levels but there is a hazard associated with salvage:
3-1) The ship is spinning on 1-3 axes
3-2) Radiation hazard because someone removed the shielding!
3-3) Fuel leak. A stray spark could make the air in a compartment go up like a torch.
3-4) Sociopathic computer (a classic)
3-5) Deranged inhabitants (possibly worshipping or serving 3-4).
3-6) Castaways (not deranged but eager for rescue and none of this 'We'll send a rescue ship, honest!')
4- Plague ship! On the bright side all systems are present and intact.
5- Patrol involved. The ship was involved in skullduggery and chicanery. The Patrol has alarmed it, bugged it and will flag and observe and flag any ships docking there. Some wise guys sell 'treasure maps' to these ships!
6- The ship seems intact apart from personal effects. However, virtually every system (5 in 6 chance) will have one or more vital components removed from it making the repair and salvage a lengthy and costly process. Optionally some vital parts have failed but look all right until the system is turned on.