Of course, over the course of several Red Ring of Death Xbox360s, I wound up with HDDs included, and out of sheer curiousity as it happens with computers as well, I scour any content included before deleting anything, often times in the case of someone's computer, I find graphics or music I wish to save in my own archive. I never exploit personal data, rest assured, but I do see that happen to wind up in the used markets of goods, and that's a bad thing! haha
Point of this topic is to go over my personal findings, one of which was Xbox Live accounts left on used HDDs did allow me for a time to use them activated with "GOLD" for online multiplayer and start over the online play aspects, for a time, this was actually a fun use of the freebie hardware I got, but eventually the ability to use an account for someone else expires. I saw this happen on more then one I got, so rest assured, no harm ensued in doing so, if dormant, I was just using it while I had it.
If it effected their online MP aspect, I just don't know, but it seems it either expires or reverted back to the original owner.
I would expect the user to do account changes before selling or pawning their old HDD or memory sources for their profiles. This should be common sense.
The latest thing is a 120GB HDD I bought to recondition to PC (laptop 2.5), but finding the previous XBL gamertag on the HDD had GTA V in their arsenal, I opted to boot up my disc and see how far they were along in the game. About 75 missions unlocked and tons of cash, all they'd done, some of it seemingly like a cheat was invoked, like tons of cash in their account...
This allows me to play their offline game as it was last saved to HDD. No Harm or Foul is invoked in doing so, this shouldn't effect them if you disconnect your online signal. As the game is starting, you're prompted for online data update, this effects saved Gamertag overall status, so if you were to play around with this in a similar situation, disconnect Broadband from the Xbox or PS3 so anything you do locally isn't effecting anyone needlessly. My system did have to run through some initial updates while online however, but I knew when I was going to explore their progress, I'd be doing so only on my local system.
I hope posting these particulars isn't against any policy, rule, or ethics, it maybe dodgy in the ethics area, but hey, it's all fair game so to speak!